Well, to buy one brand new would be about $47.76 (at Toys R Us...) but that is buying JUST the game. If you were to buy the game and the key pad that goes into the GameBoy Advanced slot (which is needed to play) the game costs about $52.80 (brand new).
If you were to buy one used it would depend upon the dealer of that used item, and its condition. It is better to buy the game brand new because in a used game, the key pad may be worn out and easily broken, or the pick stylus may scratch your screen since the protective plastic layer has worn off.
If you're thinking of selling your own game, consider its condition and how scratched up it is. Do the keys stick? If anything is not in mint condition, consider taking one or two dollars off for each fault. :) (please be sure to mention the faults of your game when you sell it to the buyer so that the buyer knows what he/she is getting).
There is no set 'trade in price' for a game at GameStop, my suggestion would be to take it in and ask what they would trade it for.
NOTE: They will give you more store credit in a trade than cash.
it's not $100 because the ds isn't even worth that much!!!! I'm wondering too but I am going to call and ask in a little bit.
at gamestop it costs 19.99 for a used one. for a new one at game stop it costs $29.99 that is just the game by it self. For the buttons and the game it is $39.99
the trade in value is $30
About $120
5 $
Depends on the value of the Guitar and the PS3 model and condition
about $70
About $10.
3 dollars probably
You can trade it to gamestop for a discount off it, but it's not worth it, because the discount is smaller than the value of the dsi you trade in.
about $20 for all consoles
it would be about 100 dollars or more.
Honestly, you'll probably get about 2$.
Amazon trade in value is less than $5 and used games start at $7.50 today February 12 2012 though Gamestop wants $18