Mr. Purple Stickpin; Do you have that in corgi sized with the message on the back?
I'll take one of each! - As for a Corgi sized T-shirt: Just boil the T-shirt untill it shrinks and put it on the Corgi - backwards! :D
All I did was go to zazzle.com and they allow you to design custom t-shirts by uploading a jpg file onto whatever shirt you want. There are no minimums (no, I don't work for them, I just found the link today by Googling custom t shirts).
Important disclaimer: Of course, I've "stolen" Father Luke's door plaque design for these examples, so we'd need to get his permission to use it, or we could use PeteM's original image (which he has graciously granted). Also, there are many other t-shirt colors available.
I'd be happy to do this as a lump (say, 10 or 20 shirts), and distribute, but again, there are no mini's at zazzle, so it's just as easy for everyone to do it themselves. In any case, I'll be travelling 4/5 - 4/15, so I can't be around to accept the merchandise until after that. I'd be glad to head this up, and charge a small premium that I would then donate back to this website, either to help mjp with site upgrades he's mentioned, and/or to provide premium membership for those who may not otherwise have it.