The cost of running a network depends on how many members your network has.
Networks are free to to try for the first month. This gives you the chance to try all the features of a network, without any commitment. After the first month, prices start at $9.99 a month, and you can pay for 3, 6 or 12 months.
Go here for more details:https://www.globaltennisnetwork.com/tennis-networks/learn-more
Don't worry, if you don't want to pay to run a network, you can always join an official network. Learn more about official networks here