We've rehomed some wethers and some pet ewes and lambs, just via general enquiries through our website.
I would suggest that you ask any prospective buyers a little about themselves over the phone, including what experience they have with sheep, why they want some pets, how much land they have to keep them on, and if they have a holding number. You need to exclude those who will get them slaughtered in a non standard way, for their own consumption and to try to weed out the time wasters.
I always try to find out something about each person, and if they don't give me that info, then they don't get the animals.
Also, don't give them away. Charging a fair price will exclude the chancers and diners, and will ensure that your sheep's new owners are well enough off to afford vet bills if needed.