First I got an ink pad from Michael's (again, used a coupon. I hardly buy anything at Michael's without using a 40% off coupon). You have to make sure for things like napkins that you get the pigment ink because it's water resistant. It doesn't bleed when a sweating glass is placed on it and it won't wipe off onto your guests faces (I tested it out to make sure).
Ended up with around 100 napkins for a about $7.
Nothing too fancy, but still cute.... and super easy to accomplish.