There aren’t other costs from me but you may incur costs such as:
Purchasing your legal policies if you don’t have them already. You legally need a Privacy Policy and it’s recommended to also have Terms and Conditions. There are free and paid options.
Service fees if you process payments through your website.
Additional subscriptions for things like scheduling plans such as Accuity or Calendly if you use them.
An email marketing service, if you aren’t using a free one.
Adding outside membership services such as Circle or Mighty Networks.