Maybe for testing or a small
private server with only 2-5 simply users it works with a hoster like
https://www.webfaction.com/. But you have to compile everything yourself and take the necessary precaution measures in order not to use too many resources (otherwise you may get kicked).
My own experience (what works) are:
* 3-5 players (everyone 4-6h activity in a week)
* RSS memory (while players digging and walking around) stays between 300 - 450MB
* Database size around 280MB (it seems memory grows with database size, or my players just tend to running around)
* Single CPU usage stays around 20 - 99% (depends what they do)
* A few mods (even mobf works, but without monsters and other cpu intensive tasks [pathfinder])