There are two types of account registration: business and customer accounts. Business account registration is required for businesses to post and sell their time. Customer account registration is required for customers to book sessions with businesses. Account registration is not required to view business pages without booking sessions.
As the businesses you determine your selling price. Each session can be priced differently and after a session has passed you can choose to charge your customer for the agreed upon amount or more/less depending on if the session went over/under in time or you provided extra goods/servcies.