FiiT VR can be had for under $20, under many different brand names, both with and without external controllers. I finally got my hands on a Pico, and it sucks. The trackpad only works with their own app, which is mostly in Chinese.
Another great headset is the BoboVR Z4, which is around $30. You can get it both with and without an external controller, and with and without built-in headphones. (Personally, I think the headphones just add bulk, so I'd buy one without.)
Don't spend too much money - the Daydream platform is coming this fall, and it promises to be a substantial improvement, with better graphics, less lag and blurring, better sensors, and better performance
. Of course, you'll need a new smartphone! (I'm saving up now!)
Good luck!
