Of course! I'd buy most fundraiser discs for local courses and clubs to help fund tourneys and pay outs. I would get behind charities too, if I knew it was going to the right places and people.
As far as the stock stamp vs. special stamp I guess it'd depend on the "special" stamp. Typically tourney stamps are lack luster in my opinion... But if it was done professionally I would prefer to not only donate extra cash but to visually represent too!