I want to second build kite - it’s an excellent piece of tech and is best described as “sane Jenkins” as a compliment. My only gripe is the pricing - it’s not designed for “small teams”. But I’d use it again in a heartbeat.
I think an in between tier would help, as it’s 4.5x the cost of GitHub per person, plus the cost of the runners. The idea of spending $42/mo on GitHub plus $180 on buuldkite is a hard sell, but the economics aren’t there.