You can get a Trek 700 or a Fuji Crosstown 4.0 for under $350, list. Some of the other popular brands may have models in that price range. The Fuji Newest 4.0 is one of the cheapest road bikes (again a few other brands have similar models) at $550 so it will be hard to get a road bike, new, for your budget. However, starting now and through the spring if they last that long manufacturers and dealers will be selling off their 2010 models to make room for the 2011 models so you might find a few road bikes and nicer hybrid models in your price range if you look hard now and in the next few months. If you are hoping to get a nicer bike than the 2010 models you find on sale for $300 then the used market is your best bet, as has been suggested.

Ken