They were only sold at Comic Market 70. There are three of them, all on black, with different colors (pink, yellow, white), text, and symbols for Nanoha, Fate, and Hayate. They are also "one size fits all," but for the average-sized Japanese person, so they're rather short for someone 6' tall.
You can still find them on Yahoo!Auctions Japan and then buy through a proxy service but it's extremely expensive to do so. Better off getting the images and getting some online place to print it for you. You'd get the size you want that way too.