Both of these shirts are variants of others that were produced previously. The white with colored bars & characters is on a previous page in black. The white version also seems to be missing the slogan "master of spin" at the top. The green one is a variant of Rainbow Prism Sonic, which appears in black on a previous page. The green isn't quite as effective at showing
off the rainbow effect for Sonic, you can see the red clashing with the background color of the tee. They're both interesting designs, great to collect if you don't already have them in another color. Green one may be available at Kohls stores.
This shirt is modern, with a stack of colored "Sonic" names for the background. Its pattern resembles one on a Spencers' wallet.
This is a ThinkGeek .com tee. All blue with lighter blue modern Sonic face, it has his name & "Sonic the Hedgehog" in Japanese, written across his spike. This is 19.99, in spring 2013.