Personally, I buy very few games at full price, and then only if I know I will be entertained for days. Borderlands, Dragon Age, and Fallout are some of the series where I've bought them at release and fully intend to do so again. Games like these are immersive and allow me to slip into them regardless of whether I want to kill some time or if I want to progress the story. Torchlight 2, which I'm playing now, is in the same category and worth more to me than most 'AAA' releases.
The thing is, quite honestly, a lot of people pay for 'graphics', but I'm not. That's fine, of course, everything is relative, but that's one of the least important aspects for me.
I'm not going to put a specific time value out there, but I like games that entertain me for at least a week before I'm done with them. Those are the titles I'm willing to pay full price for. The 5-10 hour blockbusters? I probably won't buy them until they're in the $40-$30 range, or perhaps lower.
