I'm trying to find a good (and cheap) Idea Management System for a non-profit project. I've browsed lot of good options which cost a lot of money. They are probably worth but we're planning to run this as a non-profit project, so unfortunately money investment is not the key strenght.

Basically what we want to run is a platform where users can propose ideas that are voted, commented and enriched by the rest of the community.

Thanks.