Go out and get a USB2 A-B cable for $7-15 at whichever store locally has them on sale. (should be flat end on one side and box end on the other)
Wal-Mart, Staples, Worst Buy, Radio Shack, etc. -- search online to see what they are charging.
Look at the plugs on both ends, since there are quite a few different cable ends with mini-USB and charging ports also floating around.