Well, I don't know what you definition of "cheap" is, but I would absolutely suggest the Google N1 (nexus one) over any android phone on the market. Unlockable bootloader via a simple fastboot command, FULL support from Cyanogen and his wonderful mod, ADOBE FLASH 10, and confirmed support for Android 3.0, you will not be disappointed. It was the first phone with Froyo, and probably runs Froyo the best IMHO.
edit: This thread is DEFINITELY in the wrong section btw