Search Amazon for “Windows Mixed Reality Headset”. If you are searching around Black Friday you might be able to find one for $300 or so.
These are the cheapest VR headsets out there, typically made by companies you’ve heard of but don’t associate with VR (mine is made by HP!)
They plug into a computer (unlike Facebook’s and Apple’s headsets that are self-contained computers).
If you don’t want to be plugged in with wires, Valve makes a wireless kit for the Vive. That set up isn’t cheap though.
When looking for a headset, consider weight important. The heavier the headset, the more uncomfortable it will be. Mine is one of the lighter ones and my head starts to hurt after about 2 hours.
Also the improvements in computer speed from Moore’s law were from Denard Scaling, which says with transistors 2x smaller, you can run things 2x faster but produce 2x as much heat.
Heat dissipation has been the bottleneck for a long time now.