To be honest I've never owned one so my opinion may not be correct. I would say that seems a tad high. I would think they would sell for $35-$45. Let's hope that someone who owns them can chime in.
Through a LFS I've seen them for $20-25. Big chain store would obviously be more. But then again, they're worth as much as a person is willing to spend
Pleco prices change drastically depending on what part of the country you are from. I guess any type of fish really but I notice the most fluctuation with plecos.