A user of a free product telling the developer of said free product how the developer should be spending the money that said user isn't giving them takes a special kind of entitlement.
If the developers are all students or something and can't pay for that, please let me know if there's a page asking for it and I'll pay or any of the other 1000 users who can.
In the latter case, there is also a third party tool capable of signing binaries:
https://github.com/saucelabs/isign
You do need to pay the $99/year for the certificate, but it shouldn't be necessary to buy hardware just to sign things.
There is a very simple solution. Get a dev program membership. Sign and sandbox the application and make it available in the Mac App store for $1.99. People who want a signed, sandboxed Handbrake pay the equivalent of a cup of coffee. People who want to play Russian roulette can download Handbrake for free on the web page.
Given that Handbrake is extremely popular, that small fee will probably cover the $99 per year plus a Mac Pro (or two) within no time.
Sorry but you are living in a bubble. There are thousands of software professionals who don't make that kind of money in India, South America and many other places.
Run some Google ads or something.
Please use very small words. I am struggling.
Come on, if every developer that uses any kind of Free Software decided to donate every hour the dollar amount of one HOUR of their work for the projects that THEY need, no one would be in this mess.
So you are looking at an up-front cost of $300 then around $25 per year.