you know...those would make cool give aways if we could make them cheaply enough.... Put the web address on them hand them not, kinda like business cards during dragon*con...
They cost nearly nothing, you just need some paper (from two A4 sheets I made 50 slips, though take care to make them wide enough so you can roll them easily ), Latin prayers written in some nice gothic font, some yarn or cord and sealing wax.
I have a whole box of soapstone here (long story), I'll carve some different seals, and maybe even get wax in different colours.
All in all, even if I count generously:
1 DINA4 sheet of paper - 5 US cents
1 piece of sealing wax enough for 25 small seals - 1,50 dollars (but you can get a whole pound for 10 dollars)
yarn or cord - 1 dollar (but that will be enough for all eternity)
printing - well, it costs nothing if you have a printer at home
That's 2,55 for 25 pieces (if you don't have to buy the cord it's 1,55), so it's ca 5-10 cents for a piece. And you can use anything you like to press into the wax.