How much would GameStop give you for 9 games

This completely depends on the games.

• Are the games for a current generation system?
• How recent are the games, did they come out in the past 6 months?
• Do those games still sell well? (For instance, Annual sports games and Call Of Duty games don't resell well as their isn't much difference between each iteration).

This is a very difficult question to answer as the 9 games might be worth just 10 cents a piece or their might be a couple worth ~$10. If I had to give my best guess for the trade in of 9 random games at gamestop I would put the total value at ~$30-$45. This is just from past experience.

You will almost always get better resale value selling them directly yourself via amazon or ebay though. So if you are willing to wait a bit to make the sale, use other direct selling e-commerce sites.