by that time, i wouldn't be surprised to see Radeon 4890 prices at around $100 or so, knowing AMD's strategy of price cutting these days. and don't count out Nvidia, either. i highly doubt that they'll just sit by and do nothing while AMD launches a whole new line of graphics cards in time for the holidays.
you have to remember that all bets are off with pricing in the PC Hardware market when something new comes around. there's always a lot of savings to be had as companies try to stay competitive price-wise, so keep that in mind.
See the struggle of the faithless lot as they negate their time
How low to sink to the depths of their frame of mind