Today DNN is available in both a community edition and in commercial editions. DNN was originally a free/community application and today this offering still remains. However, around 2007 the DNN core team created DNN Corporation and started offering commercial editions. Thus catering to developers and technically savvy web professionals that can support the community project but also offering extended support options to those companies that either don't have internal developers or require support beyond that typically found in open source applications.
For details on pricing of the commercial editions of DNN, you should visit www.dotnetnuke.com. If you wish to test out DNN today though, everything you need for DotNetNuke hosting is included in all of our DNN hosting plans and with our 'one click' installers you're able to quickly and easily install DNN on your web hosting space.