http://www.handhelden.com/

I picked up the book "Electronic Plastic" a few weeks ago, and I find out it's out of print! Lucky me, it was the first and only time I've even seen it in a store.

I have the Nintendo "Parachute" and Gakken "Trojan Horse" but man the batteries for both games come out to $35! Yeesh, almost better off just buying a new one and hoping for the best.