Although it is my understanding that the purpose of the supporter forum is to provide a quieter place for the professionals in the webmaster world and to give back to and support webmasterworld.
However Some people i feel would like to know what they would get for there money.
My suggestion is a 5-10$ 1 month trial of webmasterworld supporters forum allowing people to view posts and topics but not participate in them. This way members of the supporters forum dont have an onslaught of thousands of people and prospective supporters will see if WW supporters forum is suitable for them.
If it was $10 per month, it would be cheaper than a regular subscription. Furthermore, the personal could gleem all the information without getting a subscription.
A better preview method would be $5 or free to see supporter forum thread titles for a week (but not the thread themselves). This would let people get a better idea if they are ready to support webmasterworld or not.