Well, a lot comes down to how forward she is. If she is a fancy mover, fancy jumper, can do well at VHSA/smaller rated hunter shows (especially Hunt Night) in the 3’ divisions, and most people can easily ride her in the hunt field, and she passes a vet check, $25k +/- in today’s market.
The more forward she is, or the less good a mover/stylish jumper, etc, start knocking some of the price off. I sold a similar WB mare to yours, just 16.1 and a year older, with a good USEF record in the hunters and jumpers and had evented, with 3 seasons going first field, with NO soundness issue (perfectly clean vetting), for around $20k last year as she was a more forward, bold ride over fences and when hunting. Perfect for the guy who bought her, but not a super easy on-the-buckle-in-the-hunt-field ride that most want for the $20-30k price range.