@mscion....well sky's the limit for price....being said...don't go big-box store cheap...all bikes there tend to be garbage. Best thing for any bike purchase of any kinda bike is to pick a decent frame and start up from there...it's affordable to get it built the way you want from decent parts....avoid some composite frames...may seem wicked, light and durable..but realistically they aren't built for long term life. Go to a reputable bike shop...avoid the sharp glitzy shops that cater to the wallet...find a shop where the guys have grease, bruises, and cuts on their hands....then you know they aren't just salesmen...and you also know if you want your bike tuned or fixed or modified they will do it there...not ship it off to be worked on at an increased expense...by people you don't know.

@Dave....jeez man I dunno what went into it....alot of custom fun/ love there. the frame and guts of the bike are affordable...all the trim work...probably exceeded the cost of the motor by 2 or 3 times...a decent motor electric can run 2-4 grand (depending on usage the batt could last up to 10 years before you really need to swap it out for a newer more efficient battery in the future...swapping out a bionx battery and putting a new one on is easy -peasy and takes less than a minute) ...gas-powered..(on this bike customized here)... properly built half that...1 to 1 1/2 grand...I'm ball-parking that at the least it's a 4-6 grand bike...not bad considering ...need/ want a more efficient engine...better brakes, tires ....you can easily do it yourself....or affordably get it done.
Repairs are cheaper than any other vehicle and if kept well could last your lifetime.