Never attended an auction, but I might have to check it out next time to see what plants they have available. Is it normally the same stuff you'd find at the swap or harder to find stuff?
I'd guess it's the same plants you see at the Swap. I know I would not be offering any Bucephandra or C. Bullosa on an GGCA auction table so some Goober could use it for Cichlid chow.
For me the opportunity of getting F1 from wild stock cichlids to raise as potential breeders or finding a proven pair is all worth the visit.