@JKD,
Do you know if all Vortex 486slc Bridgeboards at 25mHz can be "internally clock doubled" to 50mHz? Or does it take a new crystal to accomplish? And do you think most, or all of them can handle such doubling and retain reliability in operation?
I have a 486slc 25mHz that I am about to put back into service to run a couple of old MSDOS programs/games, so I would like to speed it up as much as possible. I am also looking for my 386sx Vortex and Commodore bridgeboards so I can sell them if anyone is interested. But unlike you, I don't think they are worth the kind of money you are asking. Good luck getting $500 for all your cards together, you might find a few collectors that will be willing to pay that much, but the economy is not too good right now and as you said, the dollar is weak.