Can somebody explain to me dnforum.com's business model and how things work on there?

It's basically just a forum for discussing domain names and selling developed websites etc. There is no real business model as such, you do have to pay for membership however (if you wish to post) this costs $50 for the plan you need, however you can usually find people selling these at other forums for alot cheaper (about $15 or so) so it's worth to keep your eyes open.