[carsongross]

The OP undervalues that bit in the TLDR: "stress-free deployment". For us, hiring or contracting a DevOps guy with 1/10th the chops of the heroku crew would cost 10x what we are paying them, and I don't think we'd have a better quality of life.

Heroku is only expensive if your time has no value.

[bryanlanders]

Yes, maintenance (upgrades, security patches, scaling up instances...) if you're going DIY on AWS is also significant. The time needed for setup + maintenance varies greatly depending on the developer(s) as well as the exact project needs, but at a minimum, Heroku needs to be at least as expensive as AWS minimum costs + bare minimum setup costs before switching to AWS could be considered cost-effective.