This is my goal: I want to be able to build a multisite for

This is my goal: I want to be able to build a multisite for an event planner so when they have clients that book an event or wedding they can make a minisite for their event/wedding for reservations, etc. from a custom wedding or event theme (preferably a theme bought from themeforest.net). Is this possible to do? If so, what steps do I take to accomplish something like this?
Thanks,
Corey