This shirt is unusual for a few reasons. First off, it is by Bio World and not Topheavy, like most previous modern shirts. Bio World has done a few Sonic things before, but this shirt is widely available at JC Penny stores in winter 2010. The other unusual bit is..it's VERY bright AQUA blue, not Sonic blue in any way. This color is not photogenic at all, matching more with the colored square than the photo.
You'll have to see one to match it. It doesn't affect the green for his eyes, but it does make him look a bit unusual. You can see their shaped tag (Sonic X style) at the top and in-printing at the collar of 'Sonic' as well. It lists for 17.99, but you should be able to get it for 9.99.
Does this shirt look familiar? This shirt appears to be an exact copy of the one on that page, only this time, they used a true blue color (closer or a match to Sonic's actual color) The other shirt used a greener-blue, almost into a bright aqua. This shirt was available at Wal Mart in 2010, and should cost around $8.00 if you can find it. It should be available in kids' sizes to teen sizes. Photographed & owned by Nights111