We already had a USB wall wart (USB AC outlet charger) and I bought the following to go with it for only $5.99 (including shipping).
http://www.meritline.com/5-in-1-usb-...--p-28335.aspx
I use it for charging Sony Readers using the PSP plug, the mini USB plug charges the GPS, the DS Lite plug charges the DS Lite, and the iPod plug charges the iPods.
Very handy cable for a variety of things to be charged.
Plus, you could buy the following wall wart to go with the cable for only $2.49 for a grand total of $8.48.
http://www.meritline.com/apple-iphon...--p-31362.aspx