Would be nice to have a robust installation file signed with a certificate instead of seeing that window when attempting to install the app from MSI file:

But the certificate is not cheap, so I'm wondering how to gather the required amount of money and buy a certificate for at least 3 years. Any ideas?
Price comparison:
https://www.sslpoint.com/eu/code-signing/
Minimum is $69.00/Year x3 = $207