Like the title says, I think adding an /ah feature would promote the economy more. you can still make player shops and casinos, I just think that a /ah feature will add more interest to the skyblock server. It would also add the potential for market flipping.
The issue I can see is the ah plugin I believe works with money and im not sure if it can be set up to work with an alternate currency like grass. It would be a really cool custom feature for skyblock to have a marketplace that you can use items to trade. Up to devs and crew as to what plugins are developed though.
I'm no dev, so I have no clue if it is reasonable, but what about a way to load grass into /ah So say an item to 10k grass, you can load 2304 in, then get another 2304 and load it in, kind of like a balance? I guess then we basically have a balance storage system for grass then too
The admins can setup Chest shops that turn 1 grass to 1 dollar or smth Grass can be physical money and those chest shops can be like ATMs
Support! I think it'd be cool for survival to also have an auction house. I will say, however, that if this would require a homemade plugin it likely wouldn't be implemented due to lack of manpower.