Cost are prohibitive Valerie. I'm not pointing fingers at any specific print vendor but no matter which one ya go with they will nail you on pricing. My angle on this is obviously you are thinking of re-sale?? If so, you need to keep in mind buyers of bulk cards will expect bulk pricing so they can mark up accordingly.
If you have even a basic home printer, go to Red River Paper's website. They have templates to upload making design easy. I don't do it myself, I stay far from the GC business due to low profit margins.. Even Vista print has very poor pricing for multiple 5x7 cards :/
Best bet is find a bulk print company (large qty orders) via Google search, or follow up with Frank ^ above.