Like common carp, most folks do not want bullheads in their ponds due to muddying the water. That is probably why no one sells them. Is deepening the pond in your budget so you can have more desirable fish? If you are set on bullheads, maybe put an add on Craig's List if moving the fish is legal, and some kid might catch and sell you some. They are easy to catch on rod and reel, or net in water plants. I did both as a kid in Mercer County.
