A car is worth whatever you can sell if for.
As any professional car sales person can tell you, that varies widely, depending on where you live, what time of year, who the prospective buyer is (and how much he/she knows about cars), and, oh, yeah, condition of the car.
But, yes, there are some benchmarks, and are some resources to check:
Also check out the online sales sites to see what prospective sellers are asking.
submitted by a65ragtop