D. Cross-breds and wethers. Sheep books often run through the common breeds of sheep, but don't talk much about cross-breds (or grade sheep). However, you may want to consider them, depending upon your goals. All sheep cost the same to keep, but cross-breds (or grade sheep) can cost quite a bit less to buy. A straight cross-bred (one registered breed crossed with another) is a staple in the market lamb industry. Cross-bred ewes are considered to have "hybrid vigor", with fewer health problems. There are some interesting wool cross-breds around. One consideration -- registered sheep may be easier to resell (or find a home for). However, if you are looking for a few sheep to keep for a spinning flock, cross-breds can be a good way to go. The wool doesn't know if the sheep has papers.
On the same vein, if you are not looking to breed, you may want to consider wethers. A wether (neutered male) sheep is often quiet inexpensive to buy (most wether lambs are slaughtered). They can have really beautiful fleeces. Wethers tend, in general, to be friendlier than ewes, although all sheep have individual personalities. Friendliness/gentleness is a real plus when you have a small flock.
Picture: cross-bred ewes in spring, after shearing