Hi scrote,
Sorry you are having trouble getting answers for this. The ESA product is essentially the adapter for vC Ops as well as custom dashboards that are included with the adapter. You can run the adapter on vC Ops if you have the custom UI available to you (currently Advanced or Enterprise editions).
The vC Ops software provided by EMC with the ESA gives you the ability to run ESA. From what I understand it is essentially an "Enterprise" edition license for vC Ops.
So, to get you started, you only need to get the evaluation license for vC Ops from VMware for the Enterprise edition. You can do so at this link -http://www.vmware.com/go/try-vcenter-ops