Nathan -- I think this
is the ad you are looking for. 5000 cards for $300 -- you can edit the face or backs.
Bicycle also offers decks on Bicycle stock with custom backs. You upload a JPG file and they make that the back of the deck. I printed a deck that put my contact info inside the rectangular box on the normal rider back (instead of the two angles on bicycles) and would give them out as business cards. It works out to about 40 cents a card, but I don't give out a lot of cards so that works fine for me. LINK
Lybrary.com sells playing card stock
that you can print your own cards on, and varnish to coat it with. You have to cut them and round the corners, though.