That depends on the condition. Is it a '240'? The '83 and '84 models have numbers like 280, 300, and 310 that indicate the length. I would check the VIN and confirm that it's an 83. Use my site to try to identify it.
The $16,000 price may not be far off base. You could check NADA book value. The condition is the critical measure. At 18 years, what's a year or two off.
Kick the tires. Test drive it. Most importantly, reserve some $$$ for repairs and get your tool kit ready (and maybe a Dremel tool!).