The LFS is trying to juice you. The only way that price would be somewhat fair is if the fish was a longfin, but even then some would consider it high. As mentioned before, PetSmart sells them as dinosaur eels for VERY cheap, and having purchased several of them there, I can tell you they are pretty healthy.
Keeper
P.S. I guess I didn't technically answer your question. I'd pay 5 bucks for a 2'' senegal if it had nice coloring (they've been coming in @ PetSmart with small dots along their spine... and coming in very gray instead of dirt brown). For a regularly colored 2'' sen, I might pay 3.