Some of it will also depend on what the market will bare in your area. Saddles seem to bring more out west (like in Arizona where I am), while I have talked to some folks in the mid-west who pick up saddles for $50 at auction! So it will depend on your local market as well.
You can try doing searches for similar saddles on eBay and see what they bring. They usually go for a little less on eBay because folks can't see the saddle in person and they have to pay shipping. But you can get a ball-park.