Thanks for your reply. Yes, I've used Fred Miranda for years and while its a great resource in its own right, I don't think its a final solution to the buy/sell problem. My reasoning is:

1) I don't find it very secure, as they state in the rules you "buy and sell at your own risk." I know plenty of people who have had less-than-ideal experiences and they were stuck dealing with Paypal directly.
2) The user interface is inefficient. If you're looking for vintage film lenses, you're stuck scrolling through a bump list of random gear with no categorization. It's also not very user friendly if you're new to photography and trying to browse options.
3) There's a listing fee. As someone who's sold a good amount of gear in the past, I'd prefer to only pay if I'm also getting paid. Marketplace forums have been around since the beginning of the internet. That said, I'm not sure they hold the value necessary to prevent other solutions from being successful.

Don't get me wrong FM has helped me a ton over the years and I'm nostalgic about it just like everyone else, but to say it solves affordability, trust, and community is a stretch for me, especially the trust part. Thanks again.