Like I said, make one!

Thing is, if RS.com has stopped selling them, then the only place your gonna be able to find them is if fans make 'em and sell them (which seems to have died out since the end of the Bounce Tour). I still say your best bet is to make one yourself - or take the SAMBORA letter print into any T-shirt printing shop and they should be able to knock one up for you no probs!