Advertising isn't the issue here, Money to purchase band width is.
Advertisers will come and go, the fees it take to operate this site will only grow.
I believe we are one of the largest if not the largest member supported RC forums. This is one of the reasons it works so well. When a forum gets Sponsorships, The sponsor has the right to dictate the rules to a certain extent. "WHAT IF" Company XYZ is paying the bills here. If someone has an issue with XYZ and expresses it? Guess what, If we want XYZs support and they ask up to pull the thread we would have 2 choices. Pull it and be the companies whore or keep it up and loose funding. This would give the site almost no time to come up with the money for hosting or find a new sponsor. It could very well be the death of the forum.
The only way to do this is by adding Value Added Paid Services for those that want it and don't mind paying to support the site.
A few of these services could be:
Photo Gallery
Web hosting
Fee Based For Sale Forum.
IMO, The Info, content, Sharing of knowledge and community should always be free, anything more a user wants should be fee based.
I went to the Museum the other day. Entrance was free as it should be. I wanted to know more about what I was seeing so I rented a set of headphone for the tour. I also purchased a program book to take home. These additional items enhanced my experience and I had no issues paying for them. Did everyone have to do the same, No, Did they still benefit from the experience, Yes.
Behind the seines there are people that donate there time to the museum and others donate money as well. I don't see why we can't do the same.