Gamestop credit and the value of my items?

Gamestop credit and the value of my items?
Okay I I'm trading in
*old gameboy advanced(2002or2003 worth 30$ new) not sp + the back cover is missing but its in decent condition screen = no scrathes
*Greatest hits Dark alliance : baldurs gate ps2
*3 old dvds
*Scary movie 4 In prefect condition + spiderman 1 dvd
*harry potter and prisoner of azkaban :xbox
*lord of the rings two towers ps2
*Starwarsbattlefront 1 PC the box is a bit damaged but cds are good
how much is that all worth? and if get store credit can I combine it with a few bucks to get a 40$ game like if I get 30$ in credit I only need 10$ to get the game right? (I have no idea how the store credit thing works this is the first time I did this) I also got
+King arthur game :ps2
*Last samurai DVD
+ Ncaa 2005 okay condition workin
can you just give me a good price for all of it like 10$ or w/e just tally it all up and give me an estimate(EVERYTHING IS IN GOOD-DECENT CONDITION-ALL PLAYABLE)

Hi,

I'm not sure anyone can answer this question accurately unless they work for Gamestop

However, you can likely use the store credit as well as money to get an item that costs more than the credit. I've never been to a store that didn't allow that.