I got a Google cardboard VR headset today at PB Tech. (Just under $35). 

I installed the Google Cardboard app (and Cardboard camera) on my One+ 2 android phone. I went through the app's calibration, matching it to the "Google I/O 2015" cardboard headset.

The result was actually pretty good. I had tried the cardboard app with my Samsung Gear VR...and the result was VR that was very jittery....jumping all over the place. But if the app is calibrated to a particular headset, it seemed to perform much better...though I am also using a different phone. It might be the phone. :-)  

I was really impressed by the result. Google Cardboard works with any Android phone that has a gyro and won't fall out of the box (and has a reasonable screensize / resolution).  

I was glad it came with a headband to hold it on (just glued velcro mounts, though, so don't pull too hard) and it also had a magnetic "button" for allowing the phone to detect you want to make a selection. Amazing.....and it works! No manual scrolling, though. You have to look.  There are a lot of apps for it, too. 

For $35, how could you not?