Interesting thread, this. Ever since Clare and I first hatched the plan to introduce a new Ultimate Guide to High-End, I've been wrestling with this very question, and I'm not sure I've yet arrived at a perfect definition.
Best I can come up with so far is this: a high-end piece of equipment has been engineered to deliver the maximum possible performance, whether sound, vision or both, with the minimum possible compromise.
Like every component for sale, it will have been developed with an awareness of commercial realities -ÿits styling, functionality, usability, energy consumption and, of course, costs of manufacture will all have been factored in to the development process. However, because of the retail priorities of the manufacturer, the likely target price of the product once it goes on sale, and the expectations of prospective buyers, the engineering team in charge of development will have been able to give more priority to outright performance than to, for example, keeping a tight rein over the cost of component parts.
To me, this definition works better than trying to attach a monetary value to high-end kit. A £400 B&W Zeppelin is, for example, high-end - not by established hi-fi standards, perhaps, but by the standards of its class, undoubtedly. Same applies to a Pioneer PDP-LX508D in a market where 50in plasma screens now cost £900 from Argos. These are products aimed at delivering the best possible result within their given sector of the market, and if that means you're asked to pay more for the privilege of ownership, well, so be it.