redbubble.com has some pretty boss Metal gear (see what I did there?) I got my daughter a onesie that said "Metal Gear Rex For President" to wear during the 2012 election year. Of course, it also had a picture of Rex on it. I got this pretty cool hoodie with the codec screen that had Snake and Otacon. They also have every logo, from the MSX Outer Heaven logo (which I wanted badly, but it has a manji symbol on it) to the Diamond Dog logo. You can get them in several shirt and hoody styles and colors.
For those who wonder what the manji symbol is and why I wouldn't wear a shirt with one on it, it's way too similar to a swastika.
It's so cool, but I worry people would think I'm advertising a white power chapter :/