I sold one a while back with a scope and mount for about $750.
It's always a question of condition, accessories, and model type.
A rusted 1990's one with a single 5 rd mag might be worth $550.
A stainless steel one of new manufacture with 3x 20/5 and 3x 30/5 plus a scope mount, plus a scope, plus a case would be worth considerably more.
A folding stock (A-team model) is worth more than a standard wood stock...there's a lot of variables.
That said, and I can echo this from personal experience.
The two happiest days of a Mini-14 owner's life are they day they buy the rifle, and the day they sell it.
The one I had would not print more than 5 shots on an 8.5x11" sheet of paper at 100m. At 25m, it was printing a 4" group.
Fun to shoot - terrible accuracy.