You'd need a separate certificate, which at the moment will cost considerably more than $100. Also is your objection the $100 or merely paying Apple?
"One day," Apple could do anything. One day, they could totally prevent installing things that are not notarized. One day, they could entirely prevent non-AppStore, non-sandboxed applications from running on macOS. They haven't, but they could and indeed all signs point to these being on the very long-term roadmap. Does this mean you stop writing Mac apps today?
This has in fact happened: https://blog.charliemonroe.net/a-day-without-business/