No, it's a flat $20 wherever you go, unless they happen to be on sale that week. The caveat here is that you can pay cost (no tax) and get the points instantly.
It depends, though. I mean, there are worlds of options out there. Then again, I don't want to threadcrap. OP wants $20 for 1600 point cards that he will hopefully send the codes out for ASAP, that's about the long and short of it.