All of the shirts in this row can be shipped to the USA from that OfficialSonicMerchandise site that usually caters to just the UK or EU area.

All of these tees recently appeared for late summer / early fall line on the web site. The first 3 are just color variants of eachother. In yellowish, red or white you can get modern kick/jump Sonic in a circle with the Japanese text below him "Too Easy!". All of these have that crackling 'faux wear' on the design.
The blue & white one has a really different look from other tees, with a somewhat-shaded Sonic line art all in blue. It's a different pose, because it is from an Archie Comics Sonic art piece. The last is the "Hidden Palace Zone" Knuckles head logo one that also appears on the UK Clothing page of gear. All of these come in adults sizes, so they'll fit anyone. Watch out for super high prices though! Everything seems around 28 or more dollars each...expensive!