Within that budget , and assuming no IPD problems , i would go with an overclocked 9700k with an AIO cooler , 32gb of 3200 or 3600 ram , at least one 1tb m2 nvme drive , Gigabyte z390 pro motherboard and a Coolermaster H500m case , driving a Rift S . Many like the Hp Reverb as well , but i prefer technology that works for me rather than the other way around .
You should be able to fit an RTX 2080 or 2080s in that build as well .
Thrustmaster Warthog is by far the most popular hotas for DCS , and will fit your budget .
Cheapest monitor you can find , Crosswind rudder pedals if the remaining budget allows , and PtCtrl (input/output forum) will prove most helpful in VR .
Personally , i am awaiting the launch of Nvidea's 3000x series gpu's come september .
And Intel's new gen launches in august . I elected to pass on that due to heating concerns .