Don't know if you meant to link to a particular advert but I guarantee that the horse was only available to a Parelli person (somebody who 'doesn't slap' and isn't 'heavy handed') who was willing to pay 5-6k for a project animal.
I got one from there Gigi, trakehner mare, and she's turned out to be smashing (ex broodie)
Did go and see others, but while I could take on behavioural problems, I wasn't looking for unsound, and the owners hadn't been honest about soundness issues (even to themselves)
found poppy an excellent home through this website, she is bein trained using some parelli methods and there has finally been a big breakthrough with her behaviour now