For laminating epoxy:
https://www.fibreglast.com/
When I used to use West Systems, I bought it locally from a boat shop, rather than paying shipping.
Fiberglass and CF have come from a variety of sources. How much you buy at a time will affect the price significantly.
If you have others in your area who use composites, consider a group buy on a larger amount of cloth, which saves money for everyone.
-Kevin