Add an Auction House to the Tree Servers.

Perhaps set the number of auctions that can be created by a player based on rank.

Would love to see this run with shops for S8, but this could also replace shops for S9+.

 I would add that auctions may not make sense for everything.  Mabye one stack of Redstone block is not a good auction item, but a bundle of 16 stacks of Redstone blocks is interesting? Bulk discounts become possible.

This would also be great for non-stackable and hard to find items...Beacons...Elytra...Wilder items...let the market set the price.

I think this would be great for both sellers and buyers.