I am often asked where to get costuming supplies and I use a variety of sources, both online and in person. However, here is a list of some of my tried and true locations in San Francisco. Hope this helps with your searching.
2109 Mission St, between 17th & 18th
201 11th Street
San Francisco, Between Howard & Folsom
2315 Irving Street
San Francisco, Between 24th & 25th Ave.
146 Geary Street
Cliff’s Variety (non-hardware store portion – separate entrance)
479 Castro St
559 5th Street between Bryant and Brannon
Mendel’s Fabrics and Art Supplies
637 Minna Street
New York Apparel
1772 Haight St
539 Valencia Street
(between 16th St & 17th St)