There was a guy for a couple years who was selling CIB GBA bootlegs at a local flea market I go to. I bought a fire emblem game off him but after further inspection I found that

1. The box art looked a little fuzzy, like a bad print.
2. The box itself was slighlty larger than any other GBA box
3. The folds in the box were different
4. All CIB GBA games were $8 a piece (ones that would normally cost $20+)

The only bootlegs that are would be worthwhile to me are the 128 in 1 carts.

some of the box art for the games he had for sale weren't even the right pics, and also for the ESRB rating, some would have "RP" (rating pending) on them. Not a very good bootleg.