I have a question similar to Picking VM server hardware for development. I am trying to choose a machine that will run several (up to 4?) windows/linux VMs to be used for testing and development. A "home virtualization lab" to quote the linked question. One difference is that I want to use multiple monitors directly connected to the computer. I'm not sure of my budget, but $1000 dollars is probably a soft maximum, however less is good. I have built many machines, but I haven't usually picked components.
The linked question is a year and a half old, so I don't know what has changed.
I am intrigued by the idea of a used rack mount server as suggested by the second and fourth answers, and would appreciate suggestions regarding good models or models that are to be avoided at any cost.
If a new build is the way to go then I am mostly asking about RAM, CPU and board recommendations. I think I can handle the storage.