Are you sure that's bootleg, as opposed to just somebody with a Simpsons license putting out a cheap product? Okay, Bart wearing a red shirt is usually a sign of bootleg (IIRC, most official merchandise has Bart wearing a light blue shirt; I'm pretty sure that is intentional, to make it much easier to spot the bootleg stuff).
If you want some serious Simpsons bootleg stuff, do a search on "simpsons calendar" on Amazon; pretty much anything with the word "official" in the title is almost certainly bootleg.