We are on Autopilot's base plan, at $350/mo on annual plan ($4k/year). They said they could give us a discount once we broke 50k+ people on our list. We are at around 40k now and will be emailing them shortly to negotiate.

I'm on the Silver plan for less than 2k subscribers. They had increased their pricing while I was in trial so I asked for a discount. They gave me their $49 Silver Plan for $29.

I run a Slack community with around 8k subscribers.
Autopilot were kind enough to offer a 90% discount, so we're paying $25/month for up to 10k subscribers. We've hardly used it at all though.