Not sure about shorts but I found a pkg of thin long sleeve undershirts at Target (Fruit of the Loom or other major brand, I can't remember right now). They were in a pkg of 3 - 1 white,1 black, and 1 grey. They were in the section where all the boys underwear and socks are. I'm not sure if they had short sleeved ones or not. Just thought I'd mention it.