I made Mario with pieces from The Lego 20th Anniversary Jackpot bucket. They are bricks from building set #1707 that I bought at a flea market. So apparently that Lego set is the only place to buy the red bill of his cap. But my Lego Mario needed a Lego Luigi.
I made Luigi in Lego Digital Designer. Luigi is 2 bricks taller. I already have the eye pieces, mouth piece, and rotor left over from sets that I bought on Ebay. Lego Digital Designer doesn’t have the eye pieces, mouth piece, and rotor yet. I'm going to get the bill of Luigi's cap from peeron.com.