There is now a demo of a market at market.wascape.com. It has items, listings, a price history and 90 days of made-up trades, so you can see what a marketplace around these places might feel like.
I want to be clear about what it is. It is a demo with play money and invented traders. Sign-ups are closed, and you log in as a demo account with one click. Nothing is sold, and no real money moves.
I built it to answer a question for myself: does this idea hold together once it is on a screen, or does it only work as a sentence? I would rather find out with a demo than with a plan.