Rift: 300 custom parts, all requiring molds, tooling, materials, created by external companies and assembled on a single line. Absurdly expensive packaging, matte black heavy box with custom molded casing. High Quality IR camera, look up how much it costs to manufacture a GoPro. Tack on an xbox controller (probably not much but it adds) and this little guy again not much but its something. Comes from silicon valley. Results in a cost higher than you're expecting.

Vive: Manufactured with cheaper parts, cheaper materials, manufacturing lines that are owned by the company making it in freaking Taiwan. The lighthouses are just two motors, two lasers, LED board, single photodiode, power cable... they cost almost nothing to make. Controllers are a bit expensive but since they're ambidextrous they only need one set of molds. They don't need to subsidize development costs since that has already been handled for them. They don't need to subsidize software since thats already been done for them. All they have to do is what valve says and what their industrial designers say.