Are there any companies at Gen Con that do card grading on site? (for pokemon, MTG. etc) I know that many big comic shows now have the grading companies on site.
Sorry, I can't answer your question, but I would like to tack on a related question.
Are there usually vendors who buy valuable Magic cards? I mean cards in the $15-$50 range.
At least a dozen.
Just about every major card vendor has a presence at GenCon, and they're always buying. As for just grading (PSA), I'm not sure.
Neither has a presence at Gen Con.