This shirt can be found at the Burlington Coat Factory (a type of outlet store) but, is by the 'sega tag' company that doesn't list its name anywhere. The shirt is rather plain & classically styled. It has 1 finger up classic (redraw?) Sonic in a checkreed circle, with the logo on a simple black tee. It appears in summer 2012, & is 16.00 but will be found marked down to 8, usually. 

This is a fun classic-look black tee with the Sonic 2 winged-ring title screen logo. It has correctly-drawn cute classic Tails waving, while Sonic holds up 1 finger. Likely a boys/teens size, but where can you buy this?

This shirt would look fake if it wasn't for the Sonic logo cloth tag in the top. It uses faux wear to look old, with a sort of 50s script styled "fake ad" that says "Call Sonic Delivery service He'll get it there lickety split!" & has classic style running Sonic. The concept is certainly something different, even if it is a faux ad. This appears in 2012

This shirt just looks super grungy.
If that's the look you're going for...well it's great for that. The shirt is gray and they really went extreme-o with that "faux wear" or crackle grunge effect on the design. It's so weathered looking that parts of it are literally fading away when it's new. (why is that a good thing?) The design is thought-out though, with block font "Sonic" written in 3 shades of blue while an action pose for neo-classic Sonic is dropped in over it, nice and large. This could be a Kmart shirt in the mens' area. Can't find it there? Try the Sonic Clothing Store of Gear if you really need a weathered look.

Here is a men's t shirt with classic 'winking face' Sonic line art. A glow has been applied to make it look like blue 'neon' with glowing nose. The bottom just says "Sonic" instead of having the logo.

This sort of funny shirt has the motto "I'm too epic to fail!" , a play off of "epic fail" the internet turn of phrase. It uses neo-classic arms crossed/casual thumbs up Sonic, in a ring of stars. It uses that faux-wear / crackling to make the design seem older, for some reason. You can spot the logo really small, near his elbow. This is in mens' sizes and appears in summer 2012, but where?

This interesting tee has a double meaning slogan "I Run These Streets". It could be that Sonic merely runs through the streets indicated, or that he is assumed to be in charge of them. It uses a new technique, which is to lay a classic running Sonic art over a photo of some actual city somewhere. The photo is black & white, and he's shown at the crosswalk. Is this the first official non-event Sonic shirt that encorporates a photo for the design? You can see the official (modern logo version, oddly enough) cloth tag at the top of the collar. Where can this shirt be found, and how much does it cost?