Per request. This isn't a real market segmentation. This is a set of guesses, albeit informed guesses. You might start here, and then go do some actual market research (questionnaires and polls, interviews with people who know things, focus groups, and so on) which takes real time and real money. You'd design your research to: test these guesses, fill in details (e.g. pricing, quantities, etc), refine the segments (some might prove to be several separate ones, others might prove to simply not quite exist), and finally to try to uncover new undiscovered segments.
Commericial Art Buyers
These people buy finished art for hotels, office buildings, that sort of thing. They're buying quantities, they're probably quite price sensitive, they want quite conservative prints in a broad but basically pretty bland variety, and they almost certainly want to select the treatments (framing and matting). They almost certainly attend specific trade shows, and probably have trade publications.
These people are closely related to the previous, but they're "doing rooms" for the well-heeled. They might also "do" an office suite. There's overlap, but these people are: less price sensitive, more interested in specific color palettes and subjects, and will definitely want to select or even provide the framing and matting treatments. They're buying much smaller quantities, for more money. They have their own trade shows, but the may attend some of the same shows as the previous lot. They may have their own trade publications, but definitely also contribute to and pay attention to more mainstream "high end lifestyle" publications.
Almost no overlap with the previous lots. Often they will have specific advisers, and there may be consultation with Designers, but this is not the thrust. These people (who may not be "people" at all, but rather a collector and one or more advisory staff, as a sort of collective) are interested in the various traits that go in to collectibility. This, in turn, is defined by a rather well defined set of influencers, which is more or less by definition the only way to access this market. They're very price insensitive, and buy very very small quantities. They attend their own shows, read their own journals, and talk directly with one another. But there's no way to market directly, you must go through the gatekeepers (galleriests, curators, and so on) in all but a very very few cases.
These are the monied people who get sucked in by the Peter Liks of the world. There are several purveyors of brightly colored landscapes pursuing essentially the same market using roughly the same methods. These are people who buy very small quantities, and are variably price-sensitive. They want to think of themselves as collectors, but are unsophisticated and unprotected by advisers, and so can be persuaded that something is collectible when, ultimately, it is a cheaply made commodity. These people do talk to one another, to some extent. They go over to one another's houses, attend meetings together, drink cocktails or beer together, and talk about the various trappings of wealth they have acquired. This is a funny market, though, because ultimately each sale happens in isolation. It's the Hard Sell, and it's a pretty gruesome business.
There's other stuff going on out there. There are casual buyers who contact folks on flickr, or who buy a print off smugmug, because they think it's pretty. There's niche markets, selling people pictures of their own sailboats. There's retail stuff, selling wedding pictures, which can include prints. Some of this stuff is really selling services, and I don't really understand what's going on with smugmug "fine art" prints. It would be worth digging in to, and seeing if there's one of those market segments going under-served here, which could be usefully attacked.