That's a perfect budget for AMD Ryzen 5950X. It's faster in daily work than current Threadrippers (which won't fit into sub 3K budget well, and the upcoming ones in fall or winter will be even more expensive probably).
The rest will depend on part availability on current market, which is very volative. Memory prices rose like 30perc. in past 3 months alone, and let's not talk about GPUs :- ).
Situation is improving but it will be an issue for at least another six months so don't try to buy parts which you won't be able to get in high quantity.
If you want to build multiple machines, it's best to make them identical to make servicing and troubleshooting (and cloning installations) so much more easier.
All the builds in this forum are still accurate, the current AMD platform hasn't been updated in years. If you find build with any X550/570 board, 4x32GB 3600 CL18 DDR4 memory it will work. Any NVMe SSD, any PSU from reputable brand, any PC case you like, all universal.