Zookie: How many hours of fun game play do you have to get for you money to consider a game a good deal?
For me I am happy with $1 to 1 hour of engrossing game play. If I can get more than that I consider a great deal.
Well, you also have to factor in re-play.
Value for me comes from whether or not you enjoy the game. If you don't, it's wasted money regardless of how long the game is. If you enjoy it, it's of value even if a practiced person can win in an hour (See a game like FTL) regardless of price.
Of course, this really only applies to reasonable purchases. I'm not going to go and buy a game online for $200 when I can torrent it or get a copy on a different system that supports it for cheaper.