Electric bikes are still new to the market, that's that they are so expensive. I build all my electric bikes, and they are fairly cheap. Actually my electric bike is around the $4k mark give or take, and hits 53mph more than a hour riding time.My interest in E-bikes is directly proportional to $$.
I think I would be willing to pay 1/2 the price for 1/2 the performance (top speed/power) in order to stealthily cruise the neighborhood. So say $4k if I can ride at up to 50mph for 30 min.
But really in no case am I going to pay $8k+ for any e-bike. I could get a really lovely KTM for that kind of money.