USS Excelsior: Cup & Saucer
From Star Trek VI: The Undiscovered Country:
This a teacup & saucer made by Pfaltzgraff, their “Hampton” pattern, with a custom print. I suspect these were manufactured & sold as licensed replicas as well, so you may be able to find an imprinted one.
Scotty is drinking from a similar set later in the film, but I can’t tell if his says Enterprise on it: