By all means support your local fly shop and online resources for fly tying materials. But, also explore a bit in craft stores, bead shops, fabric stores, yarn shops and like today when cleaning out a house of this and that. This morning I came across a carpet remnant that appears to be comprised of Antron fibers. I exercised restraint and cut out a few patches of the carpet, enough to provide a decade of material.
Cut up and blended or brushed out for a shroud or left twisted for an extended abdomen, the Antron is a synthetic material that has several uses in fly tying. It was headed for the dumpster, but enough was salvaged to satisfy years worth of recreational tying.