Hi Marie. Whereabouts are you, and are your Soays registered? Are they female, and if so have they ever been lambed?
How easy they are to rehome will depend on where you live. Here in Scotland there is a lively interest in Soays, sometimes as pets and sometimes for breeding. If people just want them as pets then of course registration doesn't matter, but if they are for breeding then increasingly people are realising that registered stock will be better. Here in Scotland we are hoping to get our first RBST approved rare breeds sale in a long time, soon, which will increase the interest in registered stock.
I have recently rehomed my Soays as part of a general cutting down of numbers this winter. I had a lot of interest in registered breeding stock, with enquiries coming to us through our website. I would think that your best bet would be to put up 'For Sale' notices in every agricultural store, pet food shop and vets that you have in the area. Decide on the price you want first and meet the prospective buyers to see if they are genuine or just want cheap meat. Putting an advert in a local paper or traders ads would be more likely to get the kind of response you don't want. Putting them through an ordinary mart would mean that they would almost certainly go for meat. The rare breeds sales would give you more of a chance, but no guarantee, that they would go to someone intending to keep them, but those sales are not until the autumn.