There’s also some Ronin Warriors t-shirt designs on Redbubble. Tumblr doesn’t seem to like the direct link. http://www.redbubble.com/shop/%22ronin+warriors%22+t-shirts#_ If that doesn’t work, just search “ronin warriors” t-shirts.
Unfortunately the RW logo one seems to have a problem with the design. (Change to a light color shirt to see what I mean.) And alas no Dark Warlord/Mashou armor symbol tees. 🙁