http://www.onsemi.com/site/products/...MR2510,00.html
Check those bad boys out. You could probably build a bridge rectifier without too much trouble with those, and a relatively large capacitor.
EDIT: Say, a 0.5F 15V capacitor, or something like that, which is relatively cheap at surplus stores and stuff (there's a store here in town that has lots of high capacitance low voltage caps).