Sounds Like a Scarlet pleco L-025, or a Cactus Pleco L-024. Now that I think about it that could also be a "Three Beacon Pleco" L-091, or Pseudorinelepis genibarbis L-095. Probably one of the first two though.
Also if it is an L024 or L025, I'd say that $100 is a pretty common price for those, atleast around here.