I would rather make it myself to be honest. I was thinking smaller and cheaper camera sensors rather than using gopros also that eBay listing is a model on thingiverse so I'm pretty sure they shouldn't be selling it either lol.
Something like a runcam split would be much smaller and lighter but I was more thinking of smaller and lighter, something to just set the image sensors on and have the processors merged together in one circuit elsewhere.
It was initially meant for multirotor mounting so weight is a consideration.
All that said I did say I had decided not to bother, ive got more than enough projects on the go right now and this looks like something I'll have to make and I wasn't that interested in it, if I see something that fits the bill on my travels i might look at it again but for now i know what direction to take I just dont have the time or enough intetest anymore to pursue it at this present time nor can I get the bits delivered. Apprechiate your help though.