Anyone care to help?

We've ordered Pocketfold invitations and I'd really like to close them with a seal. Here's the problem: they're too expensive! I wanted a white, rectangular seal with our first names and an ampersand. I briefly considered trying to make them myself but then I remembered that I'm terrible at this kind of thing. Any suggestions?

ETA: I'm looking for suggestions for online companies that print this type of seal.