Weird... it was $5/mo when we signed up less than a year ago. Seems that our price hasn't changed. That said, we're moving away from it.
Why? Well, it's practically useless outside of Ruby. The UX assumes Rack/Rails-isms, so the experience is weird for Javascript errors. Beyond that, stack traces aren't good enough to debug many issues; you need logging integration. This is especially true for minified javascript.
That looks alright, but they really won't last very long without charging. Error catching services are very expensive to run.
Errbit (https://github.com/errbit/errbit) is an open source and free alternative, which is self-hosted. It's also compatible with the Airbrake API.
It's easy to set up in a few minutes, either on heroku, or on your own server. As well as being free, you can store your potentially private data in-house, and customize and integrate it as much as you want.
Why? Well, it's practically useless outside of Ruby. The UX assumes Rack/Rails-isms, so the experience is weird for Javascript errors. Beyond that, stack traces aren't good enough to debug many issues; you need logging integration. This is especially true for minified javascript.