I rarely buy games at full price, except if they are real gems like HL2 and CoD4, and then I buy the games I think will be pretty good after some months, like when I bought Rainbow Six: Vegas, and the ones that Im really unsure about and cant afford I do at time download games, witch I did with Oblivion...
The ones I plan to buy at full price within the year is (to many... ARG!! Im gonna be a poor gamer): Starcraft 2, Fallout 3, GTA4 PC and more...
And over here a new PC game is around $80 and older is around $65-50 while the "best buy" and the a lot older get a price tag around $30-15