I've noticed the treasure cards in the Wizard City Bazaar have a "set" column. Sometimes the cards may be priced differently because of the set ... but I cannot find any information on what the "set" is for, or why one might wish to have that particular card over a similar one without the set icon.
Just looking for basic information on what the set is for on Treasure Cards ... anyone? - RowanHawk
The set reprsents what hoard pack they are from. Since the bazaar works in a supply and demand format, those cards cost more because less are available.