I've tried looking for the NA SSC 3.0 too. Fruitless effort. I've seen at least 2 pop up on Ebay BUT 1 problem -
The Seller uses PayPal. I no longer have PP due in part to the company not notifying me that they were cutting off my services without my knowledge or permission. I want nothing to do with those bastards again.
So I sort of feel screwed over, that's why I'm looking around for a converter that will enable me to use the PC Engine 3.0 card. At this point, I'm willing to pay around 100, maybe more.