Interesting idea, but my unsubstantiated feeling is that there's probably a solid market for sub-class C to maybe /23 or /22, a small but well funded market for blocks bigger than /12 or so, and very, very little in the middle. That is, there's a lot of business use cases where owning a modest sized, routeable network is a potential win (e.g. site redundancy via BGP), a couple of business plans where having a very large numbers of addresses is important (e.g. you're a Something-aaS company, or an ISP/hosting play), but what's the business that needs just 64k addresses? Yes, I know they're out there (I've worked with many), but in my experience many of those are either a) really, really inefficient with their address space or b) are tacking on whatever space they can scrounge because they started out with a too-small allocation. YMMV.