Nailed it. But you forgot the part about coming to this forum and wringing your hands for at least 3 pages,
PS - And no matter where you sell or buy, there will always be a-hole sellers and buyers.
So what we need is a hobbyist/semi-hobbyist run third-party website, that allows sellers to realize better selling prices than the smaller forums, while maintaining a reasonable level of rules and added fees, and no added commentary...
Ok, I'm in. Who's going to build it?