$1000 to $1500 left for the server that you really need is tight!
If you just needed a file server with Raid that would fit within this price tag, but unless you lease a server from say HP or increase your budget I feel that the hardware you can buy for $1500 will fall short of the requirements. Running 10 x virtual machines at the same time is a heavy load even if the virtual machines are idle. Lots of RAM in use and the CPU's will be busy even with these at idle.
You might be able to get by with buying a refurb server and packing it to the max with say 32GB RAM etc, but its best to buy brand new vs an previously used server that may have a large number of hours on it of operation or taken a few power surges in its time or abuse from a prior owner in an unventilated server closet etc.
Is there a reason why you cant run whatever it is locally on the core i5 workstations that you really require the 10 virtual machines? If the workstations are to be used as dummy terminals with a citrix connection to the server etc, you can get by with cheaper workstations.
At my last IT job as systems admin we were able to extend the life of workstations by installing an HP dual Xeon server running Citrix and so these old Pentium II and Pentium III computers running Windows XP Pro were able to connect over the LAN to this server with the Citrix client and everything the user worked on was server side. Everything they did was as fast as a new computer because the old workstations were just functioning as dummy terminals almost like thin clients, and so the only local processing power used was to interface with the server which did not require much processing power at all. The Pentium II computers were between 192MB and 256MB RAM, and the Pentium III computers were 256 to 512MB RAM locally. We had up to 30 users connected at a time to Citrix, some of which were connected remotely from home working etc. But this server and licensing was expensive! I think it was like $18,000 USD.
Edited by goldfist, 01 January 2014 - 09:48 PM.