TeamTools is free for the first 50 users! Subscriptions are based on a quantity that corresponds to additional blocks of 50 users. So if you have 75 or 100 users, your subscription will be for a quantity of 1; if you have 125 or 150 users, your subscription will be for a quantity of 2. You can check out the subscription plans here, and you can enter your number of users to get a price below.
With TeamTools, you never pay for user who are suspended, deleted, or hidden (Contact Sharing disabled). So if you see more users than you expected when you first log in, try hiding any who are not actual users (like shared email addresses or resources). You can do this either from TeamTools or from the G Suite admin console.