@GrantR - You are correct. You pay $15 monthly ($12 when paid annually) for each consultant plan paid seat/license consumed by a user and have one team space to start with.

You can then add an unlimited number of team spaces that, as the one plan member, you would be the one and only member of all of these team spaces. From there, you could add one more piad member and choose to make them a member of as many of those team spaces as you'd wish. 

When you add guests, you do so at the board level only - visitors are just given a link to the board that must be set to visitor/public/"anyone with the link" access.

Creating a new team

Once you have the Consultant Plan, you can create a new team

1. using the Add teams action:

   

2. Or from the Team profile page → Company profile → Teams → Create new team:

   

    

Many thanks @Robert Johnson  - there is obviously a big difference between being able to have a centralized account with unlimited teams at no cost and having the same centralized capability but coming at a cost of a seat per new team. Good to have this clarified - I spent hours trying to see if there was any other information before posting the question.