Although Heroku offer free piggyback SSL (ex. https://[yourDomain].herokuapp.com), SSL for your custom domain (ex. https://[yourDomain].com) costs $20/month.
I've only looked at a few other alternatives but they offer the same if not more expensive options.
A basic trusted SSL cert goes for ~$10/year, which is okay.
Adding SSL was a good experience but I will most likely drop it after the first month and redirect the sign up and sign in to the free piggyback version.
Does anyone know the drawbacks to this?