Garebear: I can’t add to what appear to be good answers to your question of why does Accuphase gear cost so much, but if you are willing to buy vintage gear, you can get good deals if you are patient.
Billshenefelt: I have a C-200, and find them attractive and build quality excellent, if impressively unusual for the time (has board cards that plug into slots like a computer, and a robust chassis). I love the sound and performance, however, they are prone to specific problems, and some parts are no longer available. One of the common problems is corrosion of some of the transistor cans on one or more of the boards; I suspect that was from an adhesive or threadlock they used that became corrosive with age and/or heat. If yours aren’t too badly corroded, and all the parts are present and intact, it certainly is worth having recapped. Friday evening I replaced the power supply and larger filter electrolytics, and put it back in service while I wait for a few more caps for the boards. After some break-in all day Saturday, the sound is even better than it was before (it had original caps, but the previous owner used the preamp regularly, and the caps were high quality so did not leak from the can, but some did drift and had high current leakage).
If current Accuphase gear is engineered and built as well as the vintage units, I can understand how prices are high, though high markup here in the U.S. may make it a poor value.