Sounds like Zimbra Network Edition will do what you want.
For pricing, they have an
online quote tool for you to play around with cost variables.
Compare editions
Based on your description including the words "management," "archiving" and "HA," you are wanting the Pro version of the Network Edition.
You did not specify but if you are wanting to make use of multiple domains and have MS Outlook users, that is another set of features in the Pro version.