Cheapest around here are Pygymy Cories which are only $1.09. I think the most expensive is Sterba's Cories at $6.99, but I'm not absolutely positive on the latter.
Sterbai - they are about $7 here.I guess if I paid 12.99 for my cory's I may have goy ripped off. Don't know what kind they where. Black and white with orange fins.