The limit is in place because of resellers...one way to sidestep is to refuse to give them your name/address and pay in cash. This is what I do. I hate giving out my name/address anyways because then they call ALL the friggin' time, and I hate the MA's at the MAC stores in my area anyways.
Soooo, I don't give out my name or address, and just pay cash. If they argue with me when I refuse, I walk out and they loose the sale. (which is usually fairly large)
I'm not personally a fan of MAC CS....but I adore their m/u, and it's all I use. Yeah, I would love to have the discount (from PPID), but it's not worth the hassle for me. I figure I STILL spend less than if I was buying Chanel or Laura Mercier...KWIM?