Personally, if the snake looked great and was what I like (reduced, banded, blushed) I wouldn't have a problem paying $250-300 for A 3000+g snake that was proven. You just don't see a lot of top notch animals released at that size. A virgin animal is great for recessive breedings so you don't have to worry about sperm retention etc but I wouldn't pay nearly as much for an unproven female. Perhaps $150-175 at most if it was exactly the type of animal I was looking. It just really depends on who is selling the snake and what you're willing to pay to get an animal that fits what you need.
Regards,
B