Comparing the recommended retail price of the games or systems when they were new with the average price they were sold for second-hand, we see that while every console can be had for serious discounts if you're happy to go second-hand, some games were actually worth more second time around than they were on a GameStop shelf.
You can see the highlights of the findings below -

http://kotaku.com/5459310/which-game...-value-in-2009