don't forget benefits, hardware, support staff portion, and possibly office. We typically calculate 50% over... so that's 120k at a likely low end.
we run ghe at work and I know we spend 8 hours 4+ times a year for a test upgrade and then an upgrade from an eng that makes above either of your estimates in salary alone.
None of this includes all the work we're not doing to build new integrations or features in the ci system that we get for pay for the product. But we're not a scrappy startup either. We're paying down much of the tech debt from being a scrappy startup, it's not been cheap.