Yes there are mini mills out there, only a few though and their waiting lists are very long. They can do as little as an individual fleece, and this is why it's so expensive. I've seen prices around £40 per kilo as weighed in, so before they've got all the grotty stuff out, it pays to clean the fleeces yourself as best you can before sending.
But yes as said above why not try it yourself? I joined the local Guild of Spinners Weavers and Dyers, which had a superb workshop facility, where you could use their equipment. Enjoyable as it was to learn I didn't have the time or patience to spin all my fleeces, I'd rather be knitting, so will be using the mill when I can face sorting all the fleeces!
Other ideas for using fleeces without going through so much preparation are felting or even using a peg loom to make a rug, and it's esp suitable for coarser fleeces not soft enough to go next to the skin...
Loads of ideas - still bubbling over from Wonder wool