Most of the component cost will be in the etalon but of course the cost of components is only a small part of the cost of running a sustainable business. The PST does seem to have gone up disproportionately though (I think they used to be around half that price new when I bought one second hand for £250 a good few years ago. The pound was much stronger against the dollar back then mind you) Imagine how much the warranty claims to fix all those PST with deteriorating coatings must have cost them though!
Indeed, but if importing yourself you’ll have more difficulty and expense if something is wrong with the product or it goes wrong later (which is common with solar scopes as they are delicate and precise things). This after-service is what you pay for by buying from a local dealer. As the US is a much bigger market, and most of these products are actually shipped from there, it is inevitable they will be more expensive here.
David Arditti is quite right about after sales service. I know of one imported Hydrogen alpha scope which had the unusual problem where the image in that waveband became opaque after several years of use. The diagonal part containing the faulty component was returned via the UK supplier to the USA, and a new part obtained gratis. Had this been purchased by the individual I imagine the process may have been considerably more difficult.