Depending what kind of performance you need out of the VM you could run this on just about any hardware that supports virtualization. I would recommend looking at used business class stuff because unless you need guaranteed service and up time you will pay far too much for new bits. Check ebay and you might be able to just buy a whole server.
The most important thing for multiple VMs is plenty of memory. I'm not sure exactly how you will be using them but memory is cheap so I wouldn't go less than 12GB.
Also, I wouldn't discount the option of using a cloud provider. If this is a temporary project and you don't need physical possession of your server then you owe it to yourself to explore this option. With many providers you only pay for what you use so a small temporary project is dirt cheap. And if you guess wrong how much power you need you can always scale up.
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