Solid state hard drive for your games and software.
8GB minimum memory.
You need 3 USB 3.0 BUS controllers for most VR devices. This inconspicuous, technical thing actually causes the most problems, as some cheaper motherboards do not provide sufficient power to all ports simultaneously. Hopefully this issue is becoming less common.
CPUs do not matter too much in the grand scheme of things. Any current AMD Ryzen or Intel Core chip should suffice.
Currently adequate laptops are now dropping to the $1200 range. $800 used.
An Oculus Quest is the most mobile and cheapest option as doesn't require a computer or complicated setup, but cannot handle most games. You'd want to check compatibility with whatever VR software you wish to play, but you can buy multiple Quests for the price of 1 Rift + PC setup if group work is important.
For Oculus Rift, there is the old version, which we use and should be falling in price. And there is the new Rift S.
If you want a very mobile, less complicated setup get the Rift S.
If you demand reliable 360˚ movement, and don't mind having to fix 3 long wires and sensors around a room, then the old Rift.
My Laptop + Rift S setup I take on airplanes for the field. My Rift + PC takes up an entire room since I feed the wires from the ceiling.
I would not consider the HTC Vive because of its price premium, or PlayStation VR because of its limited content, unless they have an exclusive game you wish to try.
As for cameras, I am unclear on your intentions, but my use of 3D/VR cameras is for Motion Capture and 3D modelling work. This is a very different, large discussion.
Hope this helped.
-Shaun Kindred