All software is different. I'm only replying because my first answer is "nothing", then I thought about it.
One data point from my experience:
- developer time to prepare, document a build, release notes
- build engineer to submit, check build, co-ordinate
- build machine hardware
- build machine OS license
- cryptographic signing hardware
- QA engineer time to test
- QA automation engineer's time to set up tests and maintain them
- QA test suite of machines for compatibility matrix
- technical writer for documentation
- distribution infrastructure / CDN
- support calls for new version
Another data point from my experience:
- about 2 minutes of developer time
- gratis open source build infrastructure