To be honest I don't think you are going to find one too easily, or quickly.
I hadn't even heard of the hardware until I read your other thread the other week and I had to google it to find some information about it.
I regularly keep my eye on various sales forums and I can't say I have ever noticed a SSV board being offered for sale. Saying that one may have been listed as its game title rather than the hardware.
I would suggest trying some other forums, I wouldn't imagine a lot of people here have a lot of PCBs compared to members of Arcade Otaku, Klov, Jamma+, Neo-geo, Shmups etc. I would suggest putting some wanted threads up at those places if you haven't already.