Google cardboard is the most widely distributed Virtual Reality (VR) headsets. It is simple, affordable, and highly accessible to all kinds of learner.
Check the link to explore the basics on using the headset. Then check out the vast educational resources on VR/AR like the 900+ expeditions at Google Classroom and best ideas at Google for Education, and of course our sample lesson plans inspired by Google Classroom expeditions.
How much do you pay for a VR headset?
For classroom purposes and to have a wide exposure to the most number of students in a class, a do-it-yourself Google cardboard is advisable.
For a more powerful VR experience, HTC Vive should be the choice. However, it means that you need a powerful PC set up and for personal and small group use only.