GTX 580 was $500 the HD 6970 was about $400 (being generous) that is a 25% difference in price. The HD 6990 is $700 so 25% difference is $175, making an estimated $875 for the GTX 590. So my guess is $850-899
Cheapest 580 referance design on newegg atm I could find = 480$ (499-20$ MIR)
Cheapest 6970 referance design on newegg atm I could find = 309$ (339-30$ MIR)
Currently theres a price differnce of about 55%!!!
for about 10% faster 580 card.
I doubt the 590 is gonna be cheaper than 2x "current price of 580".
Current cheapest price of a 580$ is around the 480$ mark.
Thus Im guessing we ll see it around 900$ or abit over (dual gpu cards always abit more expensive than 2x normal version).