I supply residents of an assisted living facility with single layer fleece blankets prepped for the "braided loop edge" finish for Project Linus, and I buy fleece all year long in order to keep up with them and other groups. Joann's does put their fleece on sale at $4/yard on and off through the year. They also run half price on their red tag fabrics now and then, and usually fleece is about $7/yard before the half price. Fleece is considered to be a remnant if it is less than 1.5 yards in length and is always priced at half price of the current sales price, so if on sale, that can be a good deal.
If buying at Joann's, I would advise getting a VIP card (free) from them. It gives you a 15% discount on regular and sale price items, but not remnants, and cannot be used with a % off coupon.
Hancock's here has their remnants (which appear to be up to 2 yards) at $3/yard all of the time. There is quite a variety on that shelf, and it includes the premium and licensed fleece, as well as the cheaper varieties.
Best wishes for a successful project! I have a friend who made many single layer fleece blankets with a serged edge for a sports fundraiser such as yours. She used her embroidery machine to make wonderful motifs on one corner, including the team name. Being a single layer blanket, there actually was a decent margin.
Dayle