I read a surprising amount of posts here saying "not much useful anymore and it's run it's course". Those statements confuse and depress me. They might be true for guys that have been around here for many years and who are accomplished at the sport.
But there's lots of us that are beginners and novices that learn something here every time we hit the site. There is nothing out there even close to what we have here. No facebook page is or ever will be.
I'd echo someone else's suggestion (I forget who): free for noobs for a short time (couple weeks or months), and then membership levels that start at about $20 for year for basic access, and go up form there for ability to sell in the classifieds (but still a flat rate that is not above $50/yr).
Yea, you might lose some people, but if they leave over $20 or so, they are probably not engaged in the site anyway.