That seller's price doesn't strike me as being crazy high. I don't like kbb for vette values, because I think they're based on a formula not to be confused with what the cars are selling for in the real world.
NADA says the value is between $13,125 and $16,100 depending on the condition.
http://www.nadaguides.com/usedcars.a...013&da=-1&nx=1
Based on my looking around to find a nice low mileage C4, sounds like a deal to me if the car has a clean Carfax, you want an automatic, and you like the colors.
Good luck with your decision.