Although those cheapo ones are poor quality. I have a stack of them, even cheaper I seem to remember. $0.99 on eBay from china
The battery for them is the main cost. I bought .. 10 of them, leave one in the bike, garden shed the boot of the car, give them to mates who keep borrowing yours, hold doors open with them, whatever, they are generally are good for 10 amps or so
As Ian said, not what this thread is about, but none the less worth having a few cheapie a around
Mongoose frame, Fox F100 forks,26x2.3 tyres
100V 20Ah LiPo
Lyen 18 FET 65 Amp,5304 in 26 inch Mavic rim
To illustrate the vain conceit that the universe must be somehow pre-ordained for us, because we are so well-suited to live in it, he mimed a wonderfully funny imitation of a puddle of water, fitting itself snugly into a depression in the ground, the depression uncannily being exactly the same shape as the puddle."
-- Richard Dawkins, in "Lament for Douglas" (14 May 2001)