If I wasn’t fussy, I could pick up a pet lamb for free. Locally, too.
After that, it depends on breed, sex, ‘intactness’, age, etc. I’ve seen pedigree Jacobs starting around £150,
and Valais Blacknose over £1,500:
Critically endangered Boreray for as little as £90:
And small flocks of rare Soay (half a dozen sheep including a ram) for under £100 all in:
You may as well ask how long is a piece of wool…