In my local area government interrogates selling boards about my data what I sell and such. I wonder if this could be forever resistant to authorities provided somebody actually uses it?

That name...

I would host an instance if it's working well enough - has anyone done it yet?

How do I tell someone on the bus to check out this website?

Interesting idea. How do you deal with illegal trade?

Cool. If u can host it as a tor hidden service that is a large an influential market that might benefit from such a thing. Haven't looked but it might need some additional features to work as a decent platform in that sense.