Well, if you could swing a GTX275, that is the best price for value in Nvidia IMHO - it has more shaders than the 260, reaches almost the performance of the 285, but at a third the price. At higher resolution like you use, shaders to play a part - but that also depends on your games.

The 260 isn't a bad card either, it's just the "budget one" of the current NV gaming lineup.

400USD for an overhaul certainly sound reasonable.