Actually, I believe the first one built was '84.
Check the front bumper for a number 53, manufacture plate on firewall under hood, Saleen plaque on console by shifter - these will help determine if it's legit - you can also call Saleen and verify the VIN and etc.
If it is a Saleen and you get it for that price - you stole it!!! You can also checkout -->
http://www.performanceautosport.com <-- for what some sell for.
The cheapest one I've seen has been $9,500.
Saleen 89-215