Welcome to the Forum!
I agree we need a bit more info to narrow down the price range. A RST-4 (Standard auto,, usually mistaken for a MKI) can be worth as little as $100 in "good" condition to $200 in "Good" condition. Notice I used "good" in both prices? It's because there is also a lot of price differences in condition. To some folks,, a good condition gun will grade 80% & others it'll grade 95%.
Then we have differences in models,, barrel lengths & barrel tapers, sights,, etc.
However,, to be a bit helpful,, in general,, any good shooter that doesn't need any work will bring $150. When you add any model with adjustable sights,, it'll easily approach the $200 mark. Rarer variations,, or other things,, (such as a Red Eagle) can bring more $$$$.