It's not as bad as it seems. You're only charged if Zapier does something for you. Example that we use:
We use Github internally for software development. If something is being added to the software that any of our staff thinks will need extra testing in beta, they add a special beta-test label in Github.
Every single action we do to Github is sent to Zapier for processing. We have rules in the Zapier Zaps that look for our beta-test label. Only if it's seen does an action happen.
So in this case, Zapier might analyze 100 things we do in Github a day but may only take action on