Another thought, if you do buy from Amazon -- apply for the Amazon Platinum Visa. You get 3points/$1 spent on Amazon and 1pt/$1 spent elsewhere, and then a $25 Amazon gift certificate everytime you accumulate 2,500 points. So you could conceivably score $50 in free Amazon stuff just for buying your PB. Also, you get $30 off your first purchase with the card, and it's 1 year with no interest.
I [heart] Amazon, in case you couldn't tell. 🙂