LOL, why do you want to sell the monte carlo man, that thing is clean as fuck.
To answer the question it depends on alot of things. If the car is just owned by the average person that just "thinks it looks cool". It might not be in the best condition or maintained well. Not to mention daily driven, maybe year round. On the plus side this average person might not even know what these cars are worth. The enthusiast on the other hand usually keeps the car clean and well maintained. Its really all about the condition and history I think. A car that was garage kept, stored winters, driven on nice days out in the country is worth more than a car that was parked on city streets and driven daily year round IMO. Its hard to know how much its worth without looking at it or knowing more about the car. Ive seen 150K mile Fbodys that are mint and run like new and ive seen 40K mile F-bodys that are piles. You cant really go by KBB/NADA values for alot of these cars. I sold my 98 TA with 108K for $10,500 in 2007, just last year I sold a 00 WS6 with 85K on eBay for $9500. My 98 was exceptionally clean and the 00 was just average. If he is not trying to sell the car right now id wait a few months until its the dead of winter and hes about to move. Show up on his doorstep with $4K cash and see what the deal is. If he is trying to sell now like daturbosix said offer $5K and see where you stand. Winter will soon be upon us.