Geolocation queries are probably one of the bigger costs. Google is a rip-off here but to use them as an example, they charge $2.83 per 1000 lookups for the first 90k/month. You could easily spend a few hundred per month that way.
Maintaining an IP geolocation database requires some upkeep. You have to download the database regularly (in our case, daily) to keep the data fresh, and you need a system in place to make it useful.
That’s why we created a dedicated API tier that offers unlimited requests. The data is being used by many open-source projects, so we’re simply doing our part to support them by providing both the data and the API infrastructure service. Last year, we processed over 2 trillion API requests across all our API services. There are many projects, Open Source and Enterprise, that are making billions of requests daily, and they are on a free tier plan.