Not to get silly about it but I usually have a $/hour of entertainment calcuation that I use before buying games, going to movies, theator, buying an audiobook, or other entertainment options. Don't get me wrong, I'll pay more for an unique experience that is going to blow my mind, but if it is just esapism, I want to make sure I'm getting value.
My standard is btw is about $7 per hour of entertainment. So, a game that lasts 5 hours, I would only be willing to pay $35 unless it was something very unique or appealed to me very strongly.
Not to go on about it, but I've put 30+ hours into Skyrim and expect that I'll put 100-400 more before I either beat it or get tired of it. That works out to about 15-30 cents per hour of entertainment, and quality entertainment (for me at least) at that. So I consider it to be a bargin. Don't tell bethesda, but they probably could have gotten a lot more out of me.