If you're buying then markets are the thing. If you're selling they're not
If you have enough land, better to rear them and tout around restaurants/hotels some of which will buy the whole carcasse as it comes from the abbatoir. I have an outlet now for my Kune pork by doing this. Free range, local, rare or minority breed is the thing these days(as it should be!!)
The restaurant that buys mine is proud to advertise it a" happy pork" They give details of rearing and how they are taken gently and carefully to slaughter.