STEM Expo is a non-profit organization. To that end we don't have a lot of cash to create an inventory of T-shirts, etc. for sale!
However we've teamed up with the folks at CafePress to provide a different way to get that kind of thing.
Our Cafe Press store is now online at: http://www.cafepress.com/STEMExpo
Take a look if you're interested! Remember each sale of an item helps keep STEM Expo going!