Found it on ebay - free shipping and the cases are listed at $4.99. Legit? probably not since the seller is based in Shen Zhen, China. Pretty cool though.
I asked Hiddy and he said "fake!". Go figure. Not a bad idea though and hopefully he gets motivated to produce these
He's posted it in his blog. However google translate makes less sense then when I try to read it in japanese, so I have no idea what his feelings are on it. Pretty shit nonetheless.
Loosely translated, he says: "They don't have anything to do with SB or Usugrow so... Please... But I'd like to see one... (bitter laugh)"