Sorry but as I can see the domain HostingForumOnline.com is available, so only reg. fee for that
OnlineHostingForum.com is better than the first domain, and has a nice flow to it, but the value is hurt that the other extensions are available, so I would say mid $xx.
You better look at what has happen with your registration HostingForumOnline.com, because as I can see it, it is the HostingForumOnline.info that is registered not .com?
HostingForumOnline.com does not fit very well reg fee
OnlineHostingForum.com low $xx could make a forum talking about the uptime on hosting
and reviews on hosting. Or you could just make a site where people can get a forum for free but hosted on OnlineHostingForum. Good Luck
Ill be sure to get my $ back for hostingforumonline.com, I was kinda iffy on the subject myself but decide to give it a second opinion. My main goal was a shared, dedicated, etc.. forum.