In no particular order:
1. This seems extremely hostile to open source. I have to outlay ~90 AUD per year for the cheapest possible code signing? When I'm not making any money off my product??
2. It looks like have some movement towards a service that will do code signing much in the same way Lets Encrypt offers free certificates in the form of https://www.sigstore.dev/ - has anybody used this? any other options available in the near future that might also solve this?
3. Finally, I'm about ready to give up and just eat the cost. Any suggestions on what provider to use? (I'm based in Australia)
[1] https://github.com/Rodeoclash/vodon-pro
You can also charge for signed binaries to cover your costs.
Another option would be to publish straight to Microsoft store which I believe is free.