like I said, the bike is notihing special. Ok, maybe $50 if fully functional.
If you search is confined to stores and ads, yer doing it wrong. Gotta hunt stuff down. Best bet is often a partial bike. That is, no wheels, or no tires that hold air, but the frame is good. The hunt is half the fun, paying too much is no fun.
You got one thing right, you will look at waaaay too many wallbikes before you do find good stuff. I think C L is where weenies that think all thier old junk is gold hang out. Garage sales. If it starts at 8:00, 7:30 is too late.
THE LIPO RULES. NEVER ABOVE 4.3V NEVER BELOW 2.7V DON'T PUNCTURE
Ideal charging /discharging range for Lipo, 3.65v minimum 4.1v maximum
See battery technology section, FAQ thread at the top of the page for lipo noob info.