Yeah, these are cool. They don't turn up often, and are often obscenely expensive when they do. What do I mean by "obscene"? There is an Xpanse PN200 on ebay now for $800 or so... for that price I could buy a pile of NuBus AND PCI Macs, with accelerators, accessories, etc. Some liquidator of industrial computanium probably looks up a list price and figures they can charge more than it is worth in the real world, or an original owner who imagines they can recoup their investment in long-obsolete technologies.

Second Wave also supposedly offered a NuBus expension chassis for the SE/30, which sounds extremely cool.