To be fair, there's also Concourse, TeamCity and GoCD which all enable self hosting for free.

And Drone CI which is the most similar to Circle CI

We do -- but let me know if for some reason this isn't what you're thinking/wouldn't meet your needs: https://circleci.com/enterprise/

> $35/user/month

That's ~$40k/year for 100 devs, plus the infrastructure costs. A Jenkins license is $0 (or $100k+ for enterprise support). If it was my budget, I'd have a hard time fronting up a large fraction of a developer's salary to a third party to provide a fuzzy level of support, versus spending zero money and putting the support burden on an in-house team I can trust and directly influence.

TeamCity has great support, I trust them from JetBrains's great work with IDEs, and their top-shelf license is ~$22k (one-off with 1-year of support & upgrade; iirc the yearly support fee is discounted 50% of original license).

If you have 100 devs, you need at least 1 FTE supporting Jenkins and that's $60-120k/year alone.

We have more devs than that, and we spend way less than 1 FTE (or equivalent) per year on keeping it in good working order. Our biggest issue is when we want to do something that's not well-supported or hit bugs.

That's impressive. We run into not well supported features and bugs frequently. It's probably a side effect of our workloads.

Right now we're evaluating GitLab CI and it looks like the way forward (for us).

Don’t get me wrong, we are owned daily by Jenkins bugs. We just push as much as possible out of job config and into shared workflows & Makefiles, and treat Jenkins as a glorified cron with a web UI.

Nah, just have everyone spend 1% of their time on CI.

Like falsedan said, this doesn't cut it if you don't need an enterprise contract. My team for example: We're a 4-man self-funded startup and paying $140/month just for a license is super expensive, given that we can use Jenkins for free.

I appreciate that there's the option, but I'm thinking more along the lines of what Sentry offers: Open source, self-hostable for free, optional paid enterprise support, optional paid hosting for teams of all sizes. In my book that's the perfect lineup.

Travis doesn't offer self-hosting, Jenkins doesn't offer (non-enteprise) paid hosting.

Try Shippable's Startup edition @ $499/year. Though Jenkins software is free, you still pay for master and slave nodes. With Shippable Server SE, you can spin up nodes dynamically when builds are triggered, which will work out cheaper since you probably utilize your slave nodes less than 50% of the time.

https://aws.amazon.com/marketplace/pp/B072K2F5KF