I have 18 DS games I plan on selling to GS. They are all brand name stuff (NSMB, Mario Kart DS, AW: DS, AC: WW, Phoenix Wright, you get the point). The average price of my games sell for $15 at GS, but add $3.33 to each game makes it $18.33 ($3.33 because trading in 3 games nets you $10...