Why would a second vCenter be required, and would only machine A and B be in the second vCenter? Or are you saying that machine B needs to be in it's own vCenter instance?
SRM requires two vCenter environments - a protected site and a recovery site.
We're on a tight budget (this is a development environment, not production) which is what drew me to SRM--it's listed as something around $500 per VM. Due to the nature of our hosted environment, only one server type (Linux NFS) is not in a A/B pair. We're in the process of evaluating BRBD in case we can't find a commercial solution.
SRM is sold in 25 VM bundles. Additionally, you would encure the cost of a 2nd vCenter license. Seems overkill for protecting a single VM.
You might also look into Zerto.
