A little clarification–better GPUs help, but most VR games are targeted at a GTX 970 and equivalent, and Oculus even gave the budget 1050ti their approval.
You can get a budget VR setup like this from scratch:
($200) Lenovo WindowsMR Headset + controllers
($170) GTX 1050TI
($50) 8GB DDR4 RAM
($145) Ryzen R5 1500X (HSF included)
($80) Compatible B350 MOBO (PC Mate)
($30) 128 GB budget SSD
($55) 520 watt PSU
(~$60) Case of your choice
(You most likely have a mouse, keyboard, and headphones lying around, but if you somehow don't, you can spend however much you want on those.)
From the ground up, that's $790 total for a computer that can handle VR and a headset for it. Given that the majority of people already have all but maybe the GPU and the headset itself, the average person is probably going to spend a little over $300 total to get into VR–or the price of a new console.
Disclaimer: The WindowsMR headsets have the highest resolution, the Rift has the best controllers, and the Vive has the best tracking.
The Vive is the best overall experience for standing and roomscale VR.
The WindowsMR headsets are the best (and most affordable) setup for seated VR (e.g. playing Subnautica or Elite Dangerous with a traditional controller, flight stick, or MKB). They're also great for viewing 3D models.
The Oculus Quest, coming soon™, will be standalone VR (no computer required) for $400. We don't know what'll be compatible with it yet. Its tracking will be roughly on par with the MR headsets or slightly better, as it uses the same technology (cameras built into the headset).