Sony Xperia Advance
If you are looking for an unlocked smartphone on a buget you will have a hard time finding a better deal than the Xperia Advance. This little guy goes for only $250 off-contract, but it is also not the most powerful device (of course). It sports a 1 GHz dual-core processor with only 512 MB of RAM and a 3.5-inch screen.
Those that have an active lifestyle will love it, though. This device is dust proof and water resistant, making for one strong experience.