There's this with a fossil: http://www.shopzeus.com/product.php?sku=zeusd1-AWGR-1230069-2878

This isn't what you asked for, but it's cool and cute: http://shop.cafepress.com/item/dino...149005483&utm_campaign=white-t-shirt

This might work:
http://www.dinosaurstore.com/shirts.html

It's a good start at least...

I searched "Museum shop dinosaur shirt" without the "".

Happy hunting!

Kriston