Well, I paid $650 total (tax included) for my PS3 back in early 2007, so I'd say about that, I guess.
I honestly can't see the system costing more than $450, honestly.
I can see Sony doing a tier like they did with the PS3 and Vita ($500 & $600 PS3 tiers, $250 & $300 Vita tiers).
A $349 PS4, and a $449 PS4, with some sort of extra for the higher priced version (maybe even a bundle of PS+ or PSN games, or some hard drive space differences: 160 for the $399 unit, and 320 for the $449 unit).
In either case, I'm not getting a PS4 or Xbox 3 this year. I probably won't get one until the middle of next year, if that soon. But then, it does depend on what games are launching with it. If they give me inFAMOUS 3, Uncharted 4, and maybe a surprise like Heavenly Sword 2 or Folklore 2, The Last Guardian, then, yeah, I'll probably snag one day one.
I didn't expect to buy a Vita day one, but after seeing how many launch titles I actually wanted (5 total, and I ended up with 5 more PSP games that day as well), I caved.