[PS2] Where Is Best Place To Trade-In Fat PS2 For Slimline?

[Jam]

Where Is Best Place To Trade-In Fat PS2 For Slimline? Just Because I Asked In Blockbuster Games But He Just Thought I Meant Pre-Owned Slimline (Which I Have Now Decided Against) But He Said My Fat Silver PS2 And £20 For Pre-Owned Slimline. I Am Looking For £30+ For My Old PS2.

Thanks,
Jameseh

(BTW IDRK What Colour Slimline But Please State)