The comparison of mobile phones to VR tech is valid if you take their function out of it and concentrate on the technology. The high-end mobile phones are pushing technology to pack high-resolution screens with fast processors and GPUs while keeping power consumption low. They differentiate through screens, optics and audio. A £600 phone might cost £300 in terms of components, with manufacturing and R&D costs to recoup, and that's with economies of scale applied (i.e. they're looking to sell volumes in the millions, with components common across lines and variants). Introducing a new technology to the manufacturing process causes costs to increase until those processes become common, so (for example) when Samsung added a curved edge to their screens that will have increased manufacturing costs. We're also used to the cost of phones being spread out over the course of a 18-24 month contract where we'll actually pay *more* than their retail price.
VR in its current form is a new set of technologies, with the majority of the major components (screen, optics, plastics, tracking) requiring new processes. The volumes (hundreds of thousands) are lower than mobile phones so while economies of scale apply, they aren't necessarily as effective in bringing costs down. So I can understand that the Rift could easily run to £400 cost (which is what we're looking at if you take tax and delivery out). For those hoping that the Vive will be cheaper or on par, yes, HTC will be able to leverage lower manufacturing costs and will probably have better economies of scale on standard components which will be shared with their other electronics businesses. But the expensive bits are still the bespoke screens, optics and plastics and there's no magic way for them to reduce those costs. They're also not going to be able to sell at or below cost like Oculus are, so even if they *can* manufacture for less than £400 per unit they'll want a decent margin on it to recoup their R&D costs.
Really what I'm saying here is that competition isn't going to drive price reduction, as that relies on trimming of margins. In a couple of years time, prices to produce these bits of kit will drop, and PCs that can run them will be almost ubiquitous. That's when we'll see this generation of VR becoming accessible to the masses, and by that point the enthusiast crowd will be looking to replace their units with higher-resolution, lower latency and higher-FOV screens and better tracking and that'll in turn come at a premium (as will the computer hardware to drive them).