Bring empty suitcases.* Seriously. Then load 'em up for the trip home.
Things are less expensive in the US to begin with, but due to the weak dollar and the struggling economy, things are now unbelievable cheap. We saw stores with sales of up to 75% - 80% off. And the stores were virtually empty and had a huge inventory. (Except Wal-Mart, which was exceptionally busy...)
And hey, shopping gives a little boost to the economy as well!
*Heck, with how cheap everything is, you could also just buy new suitcases for next to nothing!