With respect to e-bike tech, the DIY impulse is to source bits and pieces cheap (usually from China or better yet free/salvaged) and kludge parts together. This is an option for the determined and resourceful, but plan on spending more time working on the never-ending project than riding the e-bike. Not everyone has the DIY wherewithal or inclination, and if what is wanted/needed isn't sold in big-box stores, forget the 'cheap'. Cutting edge design, stuff that works, offerings crafted to meet actual client requirements cost more than mass-produced, marginally functional products made by wage slaves. Being ahead of the curve costs more.
I confess to being by nature DIY and cheap. I'm a sucker for cheap. I recently needed a drill press and picked up an unbelievably cheap one at Harbor Freight. It did what I needed, but roughly, with imprecision, and after at most five hours use, it shimmies and shakes, makes noise, frustrates me, and probably won't last much longer. I thought about it and realized that someone makes a drill press that works right and well, sells it for $XXXX, and someone else thinks "I could make something that looks like a drill press and sort of works, sell it for less and get rich," and they do because people like me fall for cheap every time. When it comes to investing in an e-bike to depend on and enable you to travel, maybe best to not go cheap.
As a reformed cheapskape, I'm trying to do better. When it comes to e-bikes I decided to resist cheap/DIY-to-the-max and invest in components that work and work well, and limit my DIYing to putting all the well sourced components together. My wife and I are living below the poverty line, but I realized that to go e-bike in a mannor I enviewed I just needed to cut expenses, save up what was needed, and bite the dollar bullet. What was needed was to buy mostly new stuff as to go where no designer has gone before precludes buying used. The end result involved separating myself from a significant percentage of my income, such as it is, but I got what I payed for.
Of course, it is possible to go to the other extreme, to go for some bright and shiny bling e-bike with a fasonable brand name and styling. In the e-bike world that would be Bionx, the most touted over-priced option, but there are other over-priced wanta bes. Bionx is a propritary design, all components of the system are required and they are the only source of components that fail, such as the battery that will have to be replaced—not if but when. Plan to smile when you have to buy another battery, as in grin and bear it.
If not DIY endowed (read this forum post, all of it, to get a sense of what DIY is) and cheap is the only option, there is, as usual, a WalMart e-bike offering (not currently available). So what's not to like? Well, apart from the $445 price, you might like the color too. Otherwise it is, in a word—marginal: marginal brakes, components, gearing, frame, seating, battery (lead-acid), voltage (24V), noisy geared motor..... You get what you pay for. As a first e-bike, as a try-it-and-see-if-you-like-it e-bike, good choice. For an occasional outing—fine; but don't plan on commuting or touring or depending on a Wally World special, and plan on replacing the $100 battery every 3 to 12 months. Best to buy one, try it for a few months, then sell it no matter what. If you like e-biking, get a real one, and if you don't, don't buy another.
Beyond the adult toy offerings, e-bikes or e-trikes have the potential to offer a seriously-to-be-considered transportation alternative to the ubiquitous automobile which happens to directly kill or maim twice as many Americans as all forms of violence put together and indirectly (by enabling a collective activity intolerance) causes many more to die slow horrible deaths via ill health. And some living in the global Car Culture would be so rude as to mention the environmental costs we and future generations must pay for.
If considering an e-cycle (bike or trike) as a car alternative, consider that serious tech costs. The average new car costs $31,000. For an order of magnitude less, there are lots of used cars costing about as much as a new e-cycle. The used e-cycle market is close to nil, so new e-cycles should be compared to new cars. The $31K average new car cost is for a mass produced ticky-tacky car. For about $3K you get a ticky-tacky e-cycle, and you'll more or less be getting what you pay for. For top quality, e-cycles produced in small quantity for the discerning are most comparable to high-end cars costing $250K to $1250K. Few can consider high-end cars, but at more than an order of magnitude less, high-end quality e-cycles can be considered.
While few can afford a high-end car at $250K+, many could afford a high-end e-cycle car alternative at $5K+. When and if economies of scale kick in, e-cycles will get cheaper, so it is wait or go cutting edge now. If not waiting, don't go cheap unless knowingly buying a marginal test-the-waters Big-Box toy.
Since economies of scale don't exist except for Wally World offerings, e-cycles that aim to provide functional and dependable transportation that also help people meet minimum activity requirements are few and will cost more than $445. Just as a high-end car can cost $250K and up, a high-end bicycle can cost $9K and up before adding assist power and accessories to make it a practical e-bike.
Those who need e-motor assist can't constantly pedal hard enough to take enough weight off a saddle seat to tolerate sitting on one for very long. The alternative is a chair-like recumbent seat, but few recumbent cycles are made and so cost more. To qualify as a car alternative, some sun and weather protection must be considered which adds to cost and, to minimize adding weight, can disproportionately add more to the total cost. To carry extra weight and not fall over when stopped, a tri-cycle design becomes compelling, but recumbent trikes, you guessed it, cost more ($3000 average plus tax or s/h, plus accessories before adding power assist, weather protection, sun shade, safety features). So bottom line is early adopters need to think $5K - $15K as reasonable compared to $250K+ for over-powered Car Culture alternatives.
Going e-cycle is an alternative life changing choice that few, at this time, are willing to consider much less make. The choice is between being part of a "Culture of Enough" or a "Culture of More." The sustainability of the More!-IS-Better! way of life driven by incessant upselling is questionable. Early adopters are likely to be scoffed at as members of a "Cult of Enough." But living with "Enough" can be sustained, can be the greatest good for the greatest number, and early adopters may be more likely to pass on their genes and memes to future generations.
Currently the market defines "high-end" in terms of power and speed (as in "more is better"). E-cycles that go 40 mph (64 km/h) using just 4,200 watts are good, and over 50 mph (80 km/h) offerings are typically seen as better. A mere 40 mph e-trike might be considered acceptable by those willing to pay $12K for one while others hold out for more power and speed.
E-bikes claiming to go fast, faster, or fastest are not car alternatives, but are car wannabes. To be used on public roads in America e-bikes can use up to 750 watts to go up to 20 mph (32 km/h) or in Europe they can use up to 250 watts to go up to 15.5 mph (20 km/h). High-powered e-bikes for (legal) use on race tracks by death-defying stunt riders are not to be confused with high-end e-bikes that are true car alternatives—practical vehicles that are alternative to high power and high speed.
Like sex, speed sells and those pandering to the alleged "need for speed" are purveyors of speed porn. This is what marketing greed driven to excess does. In some countries, before the movie starts in a theatre, a short is shown of obese children stuffing their face with candy in apparent paroxysms of mouthwatering ecstasy to induce movie goers to get up and head for the concession stand. In some countries such junk food porn is not allowed for some reason. Videos of e-bikes going over 50 mph are of the same intent—to pander to hard-wired and conditioned impulses not in our best interest but serving only the money, money, and more money interests of the purveyors, or the speed fetish of hobbists.
E-cycles based on bicycle technology offer a real alternative if operated within a human-power frame of reference. Those who see a 50+ mph e-bike smoking its tires and think "gotta have one" should buy a Harley instead. Choosing "low-power" is alternative, but consider that saying "yes" to low-power is an implied criticism of the high-powered way of life that the purveyors of consumer pop culture are driven to promote.
Maybe more is better; maybe not. "Less" is an option. Failure of existing culture, of life, the universe, and everything as we know it, is an option too, but the cost of failure will be high and will involve more than money.