Rich, to follow up on hally's post, I think you might be surprised at the number of people who will pay to support the site just because they like it as-is, and understand (or can be helped to understand <img alt="smile.gif" src="http://files.kickrunners.com/smilies/smile.gif">) that it costs time and money.<br><br>
The site whose subscription policy I quoted above was on the verge of shutting down a few years ago. The owner did not want to plaster the site with ads, so he had just a few subtle ads on the front page, and one or two others, similar to what you have done. He was reluctant to ask people for money since he wasn't sure what more he could offer and still cover his existing costs.<br><br>
Finally he notified people that he was going to shut down the site soon, since it was costing him too much. Most people were (a) shocked at how expensive the site was (in time and money), and (b) quite vocal about their willingness to support the site financially. Those discussions and further experience resulted in the above subscription policy plus the ability for anyone to make one-time donations.<br><br>
The owner of the site has since been very open about his income and expenses related to the site, so I know that he has been able to hire some paid help so that he can spend his time developing the content, plus some other activities (i.e., he got his life back). In all of this time, there have only been token benefits to being a subscriber, and everything on the site is still free. People support the site because it is valuable to them.<br><br>
This is a long way of saying that I think subscriptions can be very successful. I understand your desire to provide value for people's money, but you're already providing a lot of value for free. People will pay for it. You have created a lot of good will with this site, and people will reciprocate.