My gut instinct is that if it's that cheap, they're either faulty or the shop isn't entirely legit. Don't know of an alternative sub $100 that doesn't involve popping the battery itself open (not something I'd be keen to do 'on the spur of the moment'...)
Yeah...
Thank you both for the suggestions. I've tried popping a similar battery open to...not so great results. I'm going to look at some netbooks. I tried a few out and there's a Samsung model that looks interesting, along with a Lenovo (I believe it's the S10-3, but I'll have to check).
Trying to find one with a nice screen, though...