Price of my horse...HELP!!!?

I have a 8year old AQHA mare with bloodlines that include Red Dee Hobby and Scotch Bar Times. She is a western pleasure horse that has an awesome jog(and at one time a lope) last year she developed arthritis in her one hind hock. we tried injections, however they did not work. You can still ride probably even show western walk-trot the only time she looks lame is at the lope. She would also make an awesome broodmare. If she didnt turn up lame, I would have sold her for probably 4,000 to 5,000. I am looking to trade/sell her and I am wondering what she would be worth now??