Zulip CEO also here. For folks migrating from HipChat, we've decided to match the current price you're paying for HipChat for Zulip enterprise support (and we'll also provide a high-quality migration path similar to what we have for Slack and Gitter).

See https://news.ycombinator.com/item?id=17622987 (also on HN today) to learn more about how Zulip, or contact [email protected] if you're interested in our offer.