Why do people complain about a $70 markup on the Spider, but have no problem with the Subway selling for $120? Or $200 for the DENEB? How much do you think they cost to make?
I would honestly propose that you start from scratch developping a completely new combination of hardware and software, like it was done with both SUBWAY and DENEB.
Take the DENEB card - do your own full development on Zorro II and III, get working support for Fast-Zorro II, implement all workarounds for broken Zorro III cards (including some Mediators, btw), fix and workaround unknown Buster bugs, write three independently used firmware images (Zorro II, Zorro III, rescue), get the chips needed for production (which is hard nowadays, as 5V technology dies slowly), handle all the production costs, the "Stiftung EAR" recycling administration (which is not for free, btw) and continue to provide support and firmware upgrades (for free, btw, compared to other companies) for years. And that's only the hardware point of view, there's still the whole software side which I didn't mention here, but which is also a huge part in the game (if not the bigger one).
How much do you think you will spend in time and money until you can deliver your first product?
Now compare that to some well-known PCI card solution. Hardware development: zero costs. You buy it in Far East for about 2USD per piece, completely assembled, completely tested, no additional work except labeling it with a nice sticker. No prototypes to be built and tested, no worrying about unknown chip features (aka bugs), no iterations on hardware. That's your hardware "development" costs per board. Period.
So all left is software driver development, which you can simply orientate on EHCI drivers on Linux, NetBSD, and other systems. You don't have to cope with "EHCI-like" structures as on the DENEB host controller chip (which is optimized for smaller CPUs), you don't have to worry about Zorro III DMA (as Mediators don't support this), and the only extra to work on is the little program to reprogram the EEPROM on the PCI card to contain the dongling bytes for your RDB-erasing driver (which, to be honest, also costs some extra time, for the encryption part of that malware feature, as well as the pseudo-random activation to hide your tracks).
EDIT: if you compare DENEB to Spider, please include into the comparision also the price for a FlashROM card (eFlash4000). This is already included in DENEB, leaving one Zorro slot free for other stuff...
BTW, without all the development efforts done in Poseidon (which first worked on SUBWAY cards) even Elbox couldn't have made any point in selling a rebranded PCI card.
Sorry for the open words, but I can't accept people talking about "costs" of projects which they never made on their own.
Michael