I agree with you, but you have to remember that buying a chip for personal use or buying bulk is considerably different. Speaking out of my ass now; Where's a single GTX 690 costs you $1000, someone who buys one million of GTX 690s might only pay $250 per unit. And they're dealing with chips not manufactured hardware, so they get additional "discounts" on that.
Yes, you are talking out of your ass there. You have to remember that when the PS3 came out they were still LOSING money for every PS3 sold at 600 dollars and that was using a trimmed-down Geforce 7800, closer to a 7600. By the time the PS3 came out, the 8000 series was already available and any PC gamer should remember how huge of a performance jump that one was.
If the PS4 is coming out next year they'll never be able to put a top-of-the-line chip in there and will most likely go with one that's a generation or two behind. So it might be something similar to a Radeon HD 7950 if we're lucky. I think whoever said that the next console is going to be able to display 4K resolutions is also talking out of his ass. That's most likely just a theoretical limit, running at sub-20 FPS.
Had nothing to do with the GPU on the PS3, but the CPU & BR drive which at that point costs a fortune, even a stand alone BR player costs close to a PS3 at that time.