Here is another cool chain wallet. This one is more active than the other, with a brightly colored wrap-around Sonic design placed over line art in squares. You can spot Knuckles, Amy (twice!) and Sonic in the background. This is likely similar inside (if not identical to) the wallet seen above as they appear to be made by the same source. This is available at The SonicGear Store in 2009, but it could also appear at Hot Topic.
This is the art for the Bio World Sonic modern wallet pack. It has the mainly black/white chain wallet that you've seen before, but it also comes with a thick rubber bracelet. This has the modern Sonic logo on it. This can be found at Toys R Us, and retails at about $17.99 in winter 2011.
Photo discovered by SonicBoy19