What do you mean? The HTC Vive, non-pro version only costs $599 with base stations. Where are you getting $900 from?

I agree with the high total cost though. Most people pushing PC VR, will forget about how much a real VR ready PC will cost. It's easy to spend close to $3000 even when people loathed to admit it.

If you add the controllers, how much more does it cost?

Controllers were always part of that $599 package (at launch, 4 years ago). The only other peripheral most owners consider almost a "must have" would be the Deluxe Audio Strap which goes for another $99.

My Vive cost me £400 for the whole thing, for reference.