On Facebook, I'm in several poultry groups for my state/area and have posted my chicks or roosters many times. You can't put prices in your posts as the groups you posted them in will delete them if FB doesn't.
What we do is post a picture of say your rooster, explain he's got to find a new ZIP code to reside at and any other details about him. Then put your location and tell them to contact you if interested.