Legal issues with fully paid anomalies
Some further comments based on what is being discussed privately.
Previous anomalies were free with some swag on the side. All good, you're simply buying swag.
By making it a paid event you are creating a commercial contract with the participants. In many jurisdictions, a paid event has all sorts of regulatory requirements. In Australia that includes providing water, doing a risk assessment, city council approval (including paying fees that do not apply for volunteer events), police approval, public liability insurance for attendees and volunteers, etc.
Similar laws apply in many other countries.
Niantic has been playing fast and loose with local regulations. I think they need to address this ASAP. Otherwise there is a chance the local authorities can stop the event.