These numbers are actually WAY LOW for silicon valley. If I was doing the ROI for an Amazon employee I'd start with around 350 for an SDE all told for entry level and half a mill for one with a few years experience.
But they're also way high for other places. And just right.
The point is how to do the math not the ballpark. Also that even at 100k for a dev it's maybe a wash depending on your time horizon.
My experience is that a lot of "simpler alternatives" ballooned costs beyond cost of someone to wrangle the more complex solution - and well, after initial pains, the workload drops so you can have them tackle other problems if not at full time.
Or as I said it few times at meetups, Heroku is what I use when I want to go bankrupt (that was before Heroku got sold)
But they're also way high for other places. And just right.
The point is how to do the math not the ballpark. Also that even at 100k for a dev it's maybe a wash depending on your time horizon.