Just for marketing purposes...last December, south of Tucson, I sold a 9 year old registered Arabian mare, very sweet nature, good for a beginner - she was my youngest daughter's first riding horse - in excellent health with a promise to buy her back within 60 days if she didn't work out. I had bought her for $800, put at least $2000 in her training, and sold her for...$600.
Also, about 10 days ago, we got a 13 hand BLM mustang. 14 years old, good health, very easy keeper, previous experience working cattle on a ranch, running barrels, a lesson horse and a LOT of time on trails.
He was free, his tack was included and he was delivered to our house for free. All indications so far are that he is going to be a hard-working, level headed horse - the kind inexperienced riders like myself really need. Free. With tack. And delivered.
That is the market south of Tucson. And the experienced horse buyers/sellers I know expect the market to get WORSE this winter, not better.
Hate to sound discouraging, but that describes your competition on the market. If your horse has specific breeding or experience that would justify a higher price, you will need to highlight what he has done.