Statsbot.co (top1 bot for Slack which allows you to get analytics data by asking a natural language question) lately published a story about their journey to success. They told about how they monetize Statsbot, built a business on Slack and got hired by over 20,000 teams. In the article you can find their thoughts on different business models for bots in Slack and their recommendations on using different 3rd party tools to speed up your bot development.

https://medium.com/stats-and-bots/how-statsbot-is-building-a-business-on-slack-d0d4ca1655b#.bc6yg4wmm