Highly recommend HyperPDF addon. PDF creation has been non-trivial (or very expensive) for Heroku apps. My company found out about and started using this Heroku add-on last weekend, and went straightaway into production with a valuable new feature yesterday. Very easy to setup and use. Exceptionally responsive tech support. One thing that sold us was that the top tier allows unlimited number of PDF docs/month, whereas the other alternative on Heroku doesn't have an "all you can eat" alternative.