Kuanaco it's possible that you are spamming to get people to visit that website.
Just in case yours is a genuine question, I give you the benefit of the doubt.
The answer depends whether you want your members to discuss useful things with each other. That is what forums do well.
I don't really see how buyers of domains need to talk to each other.
You can set a forum so visitors can message the admin staff, but not see each others; posts. You might find that useful as a support/ FAQ service. But there are site chat software to do that as a specialisy thing without all the extra features of a forum.
A forum is aimed to encourage contact between users, whether members only, or members + guests.