Cheap way to get into VR?

[R E S T E C P]

I got a Google Cardboard type headset last week. Just had a quick play with some of the demo apps and street view, etc... I'm hooked! Despite the crudity of the cardboard headset I absolutely love it.

Cardboard is limited by having no controllers and only one button (and being very uncomfortable) so it's really just a viewing experience. How can I get something more interactive without spending a fortune?

I have a mid-range PC, certainly not a gaming machine, so anything that requires a powerful PC to run is out.

I don't mind if it uses a phone (I have an LG G4 & iPhone 6) like cardboard, as long as I can interact with it more.

Can I get anywhere with a <£100 budget?

[Bullett]

Phones don't have the power to run 'proper vr' it's very intense graphically. So the experiences may be limited, Samsung offer various options including a controller option but you need a Samsung phone. Other phone based systems have various degrees of functionality.

A PC based system needs a good PC with a high end GPU (what do you have available?)
Control is an interesting one, cheapest option is an xbox controller or similar, not very immersive. The Oculus controllers alone are $200, the Vive ones are part of the package.
Even controllers for the Sony PSVR option will be £60 then you need the PS eye as well.

Headset options are vive and Oculus in the main. Other suppliers like OSVR are working on options and 3rd party chinese options will probably be along soon but the performance may be variable and you better hope the software suppliers add support for the appropriate sdk as support is not universal. PSVR is cheaper than PC based but still a considerable investment.

Cheapest option might be to go for something like a 2nd hand OR SDK2 but that's still £200+ if your PC is up to it.