You don't seem to understand, cards like the GTX660 are faster than old high end cards like the GTX480 with only a 2 or so year difference and yet only cost $230.
So it is not impossible.
I do understand though. Nvidia threw the price inflation rule book out the window with the GTX680 and have continued in this vain due to its success. Lest we forget the GTX680 (GK104) was originally supposed to be the GTX660 - although it might have been the Ti version with the 670 being the standard. Delays, better than expected performance and poor competition meant consumers were price gouged to oblivion.