You would purchase a System Center 2012 Standard Server Management License, which covers 2 procs and 2 VMs and includes eight System Center management products, including the one you want:
App Controller
Operations Manager
Orchestrator
Service Manager
Virtual Machine Manager
Data Protection Manager
Endpoint Protection
Configuration Manager
The actual management SCOM server is free. Since you'll be spending about $1,536 for each of the SC 2012 Standard Management licenses, that should be good news. You're looking at about $77,000.
Or you might want to look at a competitor who doesn't make you buy eight products and then adds 75% for "maintenance" and upgrades, in order to get the one feature you want.
BTW, a year ago this would have cost $157-$430 for a management license for each of your servers, and $578 for the SCOM server, or somewhere between $8,500 and $22,000 depending on what level of server management you were looking for.
Paul DeGroot Principal Consultant Pica Communications "Solving the Microsoft Licensing Puzzle"