I think if you want GC controllers you might want to take a look at Ebay or EBgames/Babbages/Gamestop used selections. Locally I have seen a few Platinum Wave Birds and wired controllers at Toys R Us, Wal Mart, and target.
But I have 1 WaveBird, Black GC, and Orange GC controllers...and the chances of me finding a 4th person to play would mean that most likley they have a GC controlelr anyway.
But, FTR
I like the Classic Controller for NES, SNES, TG16, and Genesis games. N64 games work best with the GC controller. ...and Well obviously GC games work best w/ GC controller.