Unlike most of Sheldon Coopers striped shirts, this one was actually easily found online once upon a time at UrbanOutfitters.com. Unfortunately it's not been discontinued and left in its place is only the photo of the model who wore it for their website (pictured above, left). It still may be in existence somewhere online, but as of yet I've not been able to hunt it down. Sorry!
Featured in The Big Bang Theory episodes
S01 E11: "The Pancake Batter Anomaly" S02 E06: "The Cooper-Nowitzki Theorem" S05 E07: "The Good Guy Fluctuation"