Shawn, you get a factory to produce cards and get stores to actually buy them so you can go to a store and buy them.
Try MapleStory for example. They came out with cards, but most didn't appear in stores for months after launch because stores weren't sure about investing in something such as that.
The only grounds in public media that Blockland has to stand on is that one private Blockland beta shown on "The Screensavers" 5-6 years ago.