Possibly a dumb question, but is there, or could one of the extra smart people here build, a federated marketplace to allow for direct buying and selling without the middle-man enshittification of ebay, reverb, and the like?
Oh thank god, an actual question. I was going crazy trying to figure out what that thumbnail-sized picture was supposed to be! 😃
Honestly anybody can throw together a marketplace or auction site. That part is pretty easy. The problem comes when you start trying to deal with the money. Money attracts the hackers, and your security better be absolutely air-tight. There will always be transactional fees for handling the money which needs to be passed on so that alone means you can't run the site for free.
After that comes the problem of scale. The bigger your site gets, the more people you need to hire to manage all the complaints. Who decides if it was the customer or the seller that got screwed in a deal? That comes down to a judgement call, meaning you need some good training for your employees. And of course all this also requires fees to be passed along to someone.
Unfortunately if you want a successful marketplace you can't just rely on the honesty of the buyers and sellers. It takes a constant effort, good customer service, and a way to provide that cheaper than ebay so you can attract more people to the site. Several have tried and failed to do this already, and they had a lot more money than we do.