I can say with a fair degree of experience that the amount of hours that goes into a building, whether kit or custom, is about four times that of a piece of rolling stock. The drawings alone take a long time, and my only thought is they are trying to split the cost of all the work over perceived sales.
It does seem expensive mind, but I assume capital costs of laser cutters and so on are thrown into the costs. Signal boxes should be in the 20-40 range dependant on detail, and stations anywhere between 80-120, but which ones do you do to satisfy the market? Genuinely don't know!
Anyhow, the days of having rubbish metcalfe models with their white joints exposed on a layout, while hundreds if not thousands worth of stock sits on the layout should be well behind us, but I understand the reasons why that's the case. Lack of skills/time/kit availability and so on...
They are lovely models, but if the brickwork is painted on, it's like printed stickers for decals on a model.