I think that not having sales/trading section is better for the majority. It's just inviting spammers and scammers to our site. Our moderators do a great job keeping this site clean. We already have a pretty good system of sharing resources using Private Messages.
Personally, I love my clutter. Can usually find those few odd parts I need to complete a project. While looking, I usually stumble across several items that give me ideas for future projects, or I can add to a parts list for something in the future. It's an old habit, but in my younger years I couldn't afford to buy many basic parts, and relied on salvaging components to pursue my interests.
It's amazing how many things I've repaired over the years, without buying parts. Usually feel uncomfortable accepting money for fixing something, that only cost me a little time, and I enjoyed the challenge and experience.
It's really best to leave the trade, to the individuals, and keep it private. Like the OP stated, there are many sites. Ebay, if you can get into it, but you have to work to find deals (low price generally makes up with high shipping), and Ebay gets paid when you set up an auction as well. There's Craigslist, but not sure how that works. Heard about a few times on the evening news (women selling their services)....