Im pretty sure the first card to cross the $500 barrier was the 7800GTX 512MB and everyone thought it was absurd. IMO, everything done in the past 5 years has just been a money grab for the most part. I mean seriously, its how many years later and Crysis 1 is still the best graphical FPS game? Its not that video cards are progressing that much, but more that games have stopped progressing.
2005: "How do we make more money? Lets find a way to sell more than one card to each customer instead of improving upon 1 as much as we have in the past. SLI Invented, profits go up."
2013: "Anyone remember that we can just make a good single card? Oh yea! But lets charge the price of 2 of our usual cards just to make up for having to do something. We'll then wait a few months and release a chopped down version which would normally be $500 and we'll charge $650 and people will think its a deal! lol"