wow.. i've been wondering what was on his shirt since i first saw screen shots of this game! *laughs* the mystery has been solved! i'll look into finding some shirt printing places for you. man.. i remember back in the day you couldn't walk into a mall without finding a tshirt making place..
EDIT: i might have found a place! have you seen this one? http://www.customink.com/indexb.html
click on the t-shirt link.. they even have ringer shirts (the red rings you're referring to, i belive) and you can order just one
i think you have to hit the customink singles link to do it. i didn't look into all the details.. but, as far as i can tell it's just what you need =^.^= if not, let me know.. i'll search more after work