It's been a few years but I recall there being a Punishment store in the Hooters across from MGM Grand, and there's some smaller kiosks in Planet Hollywood's shops, or used to be before it turned into PH (I bought my Sprawl shorts there I was going to wear in competition and then promptly tore my ACL and MCL so they've been used in training only).
What are you looking for?
EDIT - oH, memorabilia. Um.....sorry my post is entirely unhelpful then.