This being such an aged thread ... but my input for whatever it's worth:
- If you are doing a total cost comparison, remember to include oil, insurance and all the fiddly stuff. I rode motorcycles for the better part of 40 years ... my total lifecycle cost per bike was considerably higher than just the cost of gas. Much cheaper than automobiles, but higher than bicycles.
- For bicycles, even ebikes, (relatively) lower weight components cost more per unit than motorcycle parts. There's lots of reasons for that, but it is what one needs to factor in.
- If you are doing DIY/conversion, it's very easy to get more power than you can safely brake. The better bespoke bikes have beefy brakes. While mostly my Stromer's brakes are overkill, when I fully load up panniers and cargo trailer ... I wish for more ;>
- A bike that you really like and ride daily is a much better value than one which cost less that you don't actually ride....
Often you can find good used bikes; factor in cost of a replacement battery as many casual users destroy them either deep discharges or overcharging. But as a case in point, I was able to get a Tern Vektron d8 ($2200 or so list) for $1500 for my son. The battery appears relatively healthy ... at least so far.
I've put over 15K miles on my Stromer (indeed, I was able to get rid of my car, so the family is down to one car for 4 people, 3 potential drivers). If I'd converted my old MTB, I doubt that would have worked out terribly well (as much as I love that old Gary Fisher). So I'm glad I invested more up front.