Im looking to get a USB box that i can charge a mp3 player from, I have seen sweet ones in America (like 25$ shipping tho)

I was thinking particularly of one that takes 2 AA batteries, and was about 5$ overseas, or has anyone made one? is it easy?
Not too keen on the real expensive ones hard out batteries, but if you know where to get these in NZ would be sweet too. AA batteries would be better tho...

Any advice would be great!

Cheers!!