Seemingly in response to an earlier post of mine, Canonical has recently launched a US based store. Since they've gone to the trouble to risk taking my advice, I suppose it's only fair that I shill a bit for them.
Prices before were close to 40 dollars for a shirt after taxes and shipping. They're now closer to 25, and I think I'll put in an order at that price.
The store's new, so it's not yet perfected -- they ship a fun set of stickers via UPS Ground, a 7 dollar charge for something that could probably be sent for 42 cents. That's okay, system76 still offers stickers for the price of a SASE (?) as a draw (and sales lead) to their store.
One product suggestion: Aluminum case badges.