If ICE/GCP are licensing supplements, and you are willing to use OBS (DriveThru RPG, et al), they have a POD service for cards. Which would not only give you a nice, less risky way to offer them, but theoretically keeps them available for a long time to come. I don't know of the card quality (I imagine some Google-fu would turn up reviews), but the POD book I ordered from OBS was very nice.