I would search through the fatwallet forums or anandtech hot deals forum. They will have good info on video card deals. I pre-ordered a Radeon 800 xl recently for $240 + tax, they are now selling for ~$400 online.
What is your price range? Also, asking for a 256 mb/ 256 bit card really doesn't narrow it down to the top cards. Lots of budget, crappy cards have 256 mb, the chipset is more important than the ram, but of course it all depends on how much you want to spend.