I wouldn't bother washing fleece for selling - that's the buyers job

In fact I stopped selling fleece overseas because it has to be washed before posting.
For storing fleece, I try to wash it first although it doesn't always happen. Old raw fleece is not nice to handle nor to spin, although maybe the grease does help to keep it from becoming dry and brittle. I wash my fleeces so I can store them in a cool room in the house, in sealed plastic bags. Raw fleece needs to be stored in such a way that it has air circulating to keep it fresh, and this is more difficult to keep moth-free. I have had moths in both stored raw and washed fleece, as well as woolly jumpers etc when they haven't been stored properly in mothproof bags. That's a constant battle. The Wool Scour I use now has Ozzie Tea Tree extract in which should help to deter moths, but smells better than moth balls
For selling fleece, sell it straight after shearing. You don't then have the problem of storage, and the fleeces are deliciously fresh. For the short time you do have to store them (after skirting and picking off obvious veg bits), keep them in individual woven polypropylene sacks - making sure there are no holes large enough for moths to crawl in, and tied tightly at the top. You can also use old pillowcases etc, but the polyprop sacks look nice and smart and can be sent through the post, if you seal the top so it doesn't catch in the post office machinery. I buy mine from the supplier by the hundred. Hang the sacks of fleece in an airy but weatherproof barn until they are sold.
Jaykay - you certainly didn't waste your time washing the fleeces before storage

As long as they are in airtight bags moths can't get at them, and when you are ready to spin, you are halfway there already, without having to deal with an unattractively flattened, stinky fleece, in the middle of winter when there's nowhere to dry it.