This is the 2011 model, like Mac mini "Core i7" 2.0 (Mid-2011/Server) Specs (Mid-2011, MC936LL/A, Macmini5,3, A1347, 2442) @ EveryMac.com
but with memory upgrade to 8GB.
With quad core i7, dual drives (even with same speed, 2 500GB drives outperform a single 1TB drive for many tasks) , faster 7200 rpm drives and increased memory this is one powerful mini.
I bought this for a short term project where I need to run more VMs than my main mini can handle. I have the standard version of Mavericks installed, but you can revert to the server version through a Recovery Install if that is what you want.
$520 is a fair price. I'll keep it in case another project arises before selling for less. Would prefer a local sale in Ottawa, but will ship at buyer's expense. Since it's a mini, expense will be modest (around $20 insured to GTA, for example).