That would be Mr. Manabu Sakai of ARTMIX Japan, from whom I purchased the TS Adapter PDS slot riser card, several photos shown here:
http://www.flickr.com/search/?q=stratos&w=66071596%40N00
It is expensive. But whether it is merely a "toy" or not depends on your plans for it. Presently, it is a "toy" for me since I am not using it because I have a DiiMO 030 accelerator card in my SE/30 now (along with my MacCon). But when I used the TS Adapter in conjunction with my Daystar Turbo 040 40MHz accelerator and MacCon Ethernet cards, it was more than a toy, believe me.