I usually ask about $50 for a high end baby, maybe about $85 - $100 for a high end yearling, and would probably ask $150 - $200 for a good, proven breeder adult. Variables would include color, gender, age, breeding history, etc. If it was "the best I ever saw" and a proven, productive, adult female, I might ask even more. Of course, you would have to add shipping to those prices, unless you lived close enough to pick it up.
Hope that gives you some ideas of price ranges.