gulper cat - This fish will not win any beauty contests.. What do you feed that -Small dogs ? 
From what I read, anything up to same length, possibly bigger is fair game.
If I found a breeding pair/trio of L134 leopard frog plecos, I'd grab them. But...I don't know that they're that rare.
I have always liked the strange plecos. I just am too cheap to buy them. After I took my little break from fish, I was surprised on how some that were once so expensive are not reasonable. Then others are the opposite.
Yep, seems to fluctuate. At the moment I'm shooting to get some that don't grow too large (under 5"), and would be happy for life in a 24x12 tank in a pair or trio. And have nice patterns. And don't bankrupt me (so no L46 zebras).

If I had an open tank and the price was under $75...probably a gulper cat. But no one has them around here or they're $150+.
Hmmm... I thought gulper cat just referred to the big cats. But, now I see its an actual type of catfish. Pretty strange looking. I'll have to find out the story on these. They gulp air, or are those pictures really a belly that full of some kind of food?
They gulp whatever food you can put in with them.
http://www.planetcatfish.com/catelog/species.php?species_id=961 Also some threads on MFK about them eating arowanas and such.