When I configure VM's , I usually try for at lease 2 cores per VM and ~ 2 gig memory per VM (one to handle the application and one to handle OS maintenance) Many application will benefit from even more additional cores in the VM.
So, for 5 VM's you'll want 10 or more cores.
I would go with a dual - 6 core WSM processor server with 12 g ram (or more)
You could likely get by with less, but you will see performance degradation .
Depending on where you plan to put the system, Rack or pedestal mount.
Intel manufactures many semi integrated rack servers where you add your own cpu, memory, hdd & OS
As well as other building lock for pedistial systems