When I was teaching in Thailand, the best ones I saw were a "Super 250 in One" and a "333 in One". Since I had been living there a while, I insisted that the vendor plug the 333 in his demo Gameboy. He refused, but he did allow me to try the 250 (one was opened, one was wrapped in cellophane). I would guess that there were actually about 90 real unique games in the cart, with duplicates. I bought the 250, my friend bought the 333 over my suggestion that he pass on it.

My daughter loves the 250. My friend bought a very nice (cheese green, aptly described, Ads) plastic case with no ROM at all. If you're dealing with black market items, you get what you pay for, as long as you check it out first.