I run a Zazzle store offering t-shirts with the logos of public domain heroes, superheroes, and sci-fi heroes. The designs can also be transferred to other products that Zazzle offers, including mugs, stickers, pins, etc.
https://www.zazzle.com/store/public_domain_heroesThere's also an associated Facebook page for those who are interested in following on FB:
https://www.facebook.com/PDHeroShirtsStop by and see if there's anything there that interests you. And if not, check again later; I'm adding new designs all the time!