I would love to buy a couple t-shirts with your logo - "Salk Signature Sound". A small logo upper left chest would be great, or perhaps a second logo on the back as well aa
Have you ever considered having t-shirts made for customers?
If you don't want to have to mess around with selling them all year round, perhaps advertising a sale here, or on your site once or twice a year would work.
With this weekends event, Salk owners would have loved showing up in one of your t-shirts.

Two larges please, a black one and a red one, anyone else?
Mark