My goat cost $15. Being vegetarians, we can feed him table scraps instead of grain, he particularly likes banana peels, bread, rice, and squash, and dislikes tomatoes. He mows our yard for us, which is a benefit because I never have to mow, just move him around among the various stakes we have.
He does dig up the yard a bit and likes to eat lilacs and other ornamentals.
If it were warm year-round, I'd never have to pay anything for him except for the water and the occasional worming treat.
He has turned out to be a better companion than the dog we used to own. We even take him for walks.
On the other side, he makes little fibre. It's hardly worth it to shear him but I do it in the spring because he sheds so badly anyway.
Personally, I'd buy some pregnant Shetland sheep if you want fibre. Get pregnant ones because the offspring are much more docile towards you than the parents would be. Their wool's worth an aweful lot of money, some $30-$100 per pound, they are light and easy to shear and make wonderful wool that is a joy to spin. Keeping sheep is also quite cheap. Our Shetlands cost about $80 last year. Avoid extra genetic tricks like "the valuable white sock Shetlands." Whatever. You won't use that wool, anyway, and they're really not so valuable.
What you will spend money on is fencing, unless you picket them like we do.
But the thing to remember is that when you are paying $300 for a blanket, the money is going to the tools- to the shears, the wheel and the loom, and to the labor, not to the cost of raising and keeping the animal.