I sold mine in October 2006 for store credit at GameStation.
I kept all but 3 of my games (I sold REmake, 007 Agent under fire and Burnout with it) and kept two of my three controllers (one being a wavebird)
I got £24 total credit for the GC+controller.
I got £6 for REmake and £3 each for the other two
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4 months later I procured a Wii, and used my £36 credit towards LoZ:TP.
I do miss my GC though, it is still the cutest of all consoles.