I think it is more than Promo CCG Cards. There are Spielbox mini-expansions, postcards, Essen giveaways, etc. I'd love an expansion exchange and think that a math trade might not be that over-engineered as the postage is low and I'm sure someone wants to trade a silver robot for a St. Pete Banquet, or whatever.
Ok, how would we go about labeling such a Math Trade? "Small Promo Items"?