The template that runs Idea Jam will be available for purchase during the first quarter of 2008. It will be priced aggressively. We are also working on offering a hosted solution as well.
Salesforce's Idea Exchange which will be part of their Winter 08 release costs anywhere from $500-$900/year per user.
IdeaJam is the best idea flow application at the moment. If pricing is dynamic to the budget of the hosting company, it's as good as OpenSource. But I think the competition is also hard, and soon there will be also similar OpenSource solutions available (not from me at the moment though :), but then you have to consider also the handicaps/benefits the benefits if it's Crap-DB based, or Domino/DB2 based.