[jacquesm]

Heroku is probably really great as long as you are small. Once you get serious you can host much cheaper on your own machines, but there will be additional (hidden) costs to factor in because you'll be spending more time on doing all the stuff that Heroku does for you. That's their added value, super easy deployment and keeping your stuff up and running. Cost wise it is fine as long as you're small enough to not notice you bill as a 'significant expense'. When that happens you should look in to running your own server, maybe first a virtual one, then move on to a dedicated server. That should allow you to scale to quite impressive size without breaking the bank.

[amock]

Once you get big enough you might be able to negotiate with Heroku for a better deal. They might not be willing to give you au better deal, but if you're already there you might as well try before going through the expense of moving somewhere else.