On a Payment Event saved search, is there a way to add a filter for Amount or Transaction:Amount? I opened a case with Netsuite and they said no, and tagged it to Enhancement #153588. This seems basic...but maybe I'm missing something obvious. It would be nice to use this when you know the amount but not necessarily the date it took place.

If you're reasonably technically savvy and just trying to address a business need (ie. searching for exceptions/chargebacks or similar) it might be worth getting to grips with Tim Dietrich's SuiteQL query tool https://timdietrich.me/blog/netsuite-suiteql-query-tool-suitelet/