Many add-in board partners have shipped their Radeon 3850 512MB cards but they will get huge volumes of these cards in some two weeks' time. Currently, everyone has ultra low priced Radeon 3850 256MB cards in stock, but for many people more memory means a significantly faster card, which is often not the case.
The price difference between 256MB and 512MB is so marginal that we simply couldn’t advise anyone to go for the 256MB card, but if this is your only choice it is something that you should consider.
The biggest problem is that far too many cool games are out and people are out of patience; but luckily for ATI, Nvidia is struggling to ship its G92 / D8P based 8800GT cards, as well.
The ATI market should stabilize in about two weeks, so you should be able to buy a Radeon 3850 512MB at the latest then.