A shameless plug for my Redbubble collection! Probably the largest collection of Reliant-related tee-shirt designs on the web.
You can order the tees (and sweat shirts, etc.) in a variety of colours and sizes direct from Redbubble. I make a few cents commission for the artwork, but believe me, it's not a living! I do it for the pleasure of drawing.
They also supply stickers, posters, cushions, etc., with the designs.
I have quite a library of Reliant illustrations and caricatures, so if there's something you would like (or a different colour than on the site), drop me a line here or via bubblemail (available on the site once you sign up)
I'll even personalize a drawing if you wish, i.e. number plate.
http://www.redbubble.com/people/car2oonz/portfolio
a couple of examples:
Note the photo isn't on the tee - just to show the personalization.