I think I've talked about how touchy of a subject knockoffs are. I'm on the fence. Designers have been copying each other for decades, making it hard to say who's was there first. I can't say I've never been guilty of buying a knockoff either. (Can you?) I certainly can't cast the first, or any stone for that matter, so instead I'll just blog about the similarities.
First up, we have the "Studded Pumps" from Forever 21 (available here). They are cute and pretty decent quality for the price. They aren't quite as stud-filled as the pair they are trying to be, but perhaps that is what is keeping them from being sued? They don't quite have the "I will CUT YOU" factor of the Louboutins, but they do give off an air of "I will probably cause you (but not your wallet) some moderate damage!" Either way, for $30 (and I'm sure I'll get stoned myself for this) they aren't half bad.
Sizing on the Forever 21 shoes is true-to-slightly narrow. I took a US 7, but would need padding. I haven't tried on the pigalles, but if you can find them -- they run larger like most current season Louboutins.