I don't know what the price figures would be, but I think a more dynamic shirt for Ogre would be much more appealing. So far, we've only really gotten simple shirts that have a classic Ogre design applied to a normal t-shirt (with the exception of the beautiful polos, but these are a bit of a niche).
One of my favorite t-shirt designs is one that has a wrap-around at the hip (check out this
yo-yo shirt in that video image, I own this shirt and it is one of my favorites). Imagine having an image of section of the hex map with counters on it along the hip, and then in the classic font "OGRE" across the chest?
I would request that it is something other than black. Maybe blue and red as color options.