Amazon has the SkyTech Omega 6th Gen Core i7 8GB GPU Gaming Desktop (ST-OMEGA-VR1080) for $1699 - $306 off with coupon 67U5XOFB = $1393 with free shipping. List price: $3500. Features Intel i7-6700K 4.0GHz Processor, 2 TB 7200RPM Hard Drive, Nvidia GTX 1080 8GB Video Card. Windows 10 Professional 64-bit.
Has good Amazon Reviews.
Amazon has the HP VR1000-100 Windows Mixed Reality Headset & Controllers (2018 model) for $199 with free shipping. Has good Amazon Reviews.