if you're counting pennies just use dokku on a vps, there was even an article here on HN recently. By the time you outgrow it you'll have outgrown the vast majority of the new paas sites that are springing up trying to be the next Heroku and your choice of where to go next will be easier. In the meantime, you'll have saved all that effort on just picking where your app is hosted and, instead, spend it on actually delivering your app. crazy thought, i know.