If a host of people will gather this year in England why wouldn't we make an arrangement that some stuff (t-shirts, bags) are made / ordered there by the locals and then carried out of the country by the visitors?
We could make them cost a little bit more than the expenses and then send the profit for the 'Downs internet payments?
I think you can make prints from a bitmap image (or whatever format is the best nowadays) to almost anything. A kind of quality printing place would be preferable as at least I'd hope the print would last a bit longer than those "wash and go" prints...
While on the subject, why don't we make our own "design the Barrow Downs t-shirt / mug / bag" -competition? So alongside the traditional sword-image we could have also a new one - decided by a vote from the entries of the 'Downers willing to take part? Looking at any of the Paper Telephones shows that we do have some quality illustrators here with a sense of humor.