The answer to that question is complicated. Mostly because vSphere with Operations Management (vSOM) actually requires vCenter. So, when you purchase vSOM to manage your infrastructure, you are actually using vCenter to manage, but the Operations Management component is integrated, so the health "badges" from that component show up within the vCenter view of your environment. I believe there may be various bundles available, but this is not my area of expertise.
Per the last page of the datasheet http://www.vmware.com/files/pdf/vsphere/VMware-vSphere-with-Operations-Management-Datasheet.pdf :
"vCenter Server is a required element of a complete vSphere with Operations Management implementation and is licensed separately on a per instance basis."
You can find more information here
If you require more information about packaging or pricing, please contact your VMware Sales or Partner Enablement representative for more information,
Here I would like explain about why You need vSOM instead of vCenter or if you already have vCenter!!!
With vSOM your customer can view an intuitive operation dashboard that leads to root cause analysis and actionable recommendation and also help to be proactive instead of doing reactive as well your customer can calculate CAPEX/OPEX cost and plan future budget. vSOM come with vRealize Operations Manager 6.0 license. vRealize Operations Manager 6.0 is the latest release of VMware's integrated operations suite, converging performance, capacity, and configuration management. This release introduces the following enhancements.
- Scale-Out Deployment Architecture
- Unified User Interface
- Licensing Management in 6.0
- Smart Alerts
- Enhanced Reporting
- Capacity Planning and Project Management Capabilities
- Custom Policies
- Automated Remediation of Problems
- User Access Control Management
- Unified Storage Visibility
Hoping its help to convince your customer.