Thing is 9800GX2 is aimed at people who want 1 of the best card on the market or people who want the absolutely best video card setup in which case they'll get more than one. Money is rarely the issue with people who are willing to spend over 400$ for a video card.

If anything is going to kill the sales of the 9800GX2 it's going to be the rumour of the R770 or the GT200. The 30% price increase for a 10% performance increase isn't something that's going to deter people from getting this card. The possibility of spending $400+ on a card that is going to be obsolete in 3 months time after its purchase is.