Edit : This suggestion does not change the fact that right now in Horizons a large group of players can set up shop in a busy area like Bristugo and all have macros announcing their shops on the market / local / whatever chat channels. The suggestion does not affect this functionality of the game in any way.
In Horizons we have the option to set the contents of a backpack pouch as visible when trading with other players. We can price individual items. We can set up a macro that every 20 minutes will inform people on the local chat channel that we are trading, come and browse.
We can't automate the process though.
I gave another game a quick go, and although it wasn't to my liking I did find that it was great fun to set up a stall with all my goods priced up, and I could then go do work for a couple of hours and come back every so often to find what was selling, who had bought what, and on some occasions my stall was empty. Every time I came back to the computer I found someone browsing my stall and I'd chat with them for a few minutes. I'd like to see this possibility in Horizons where a casual player does not need to be there 100% of the time to approve any trades. As far as I'm concerned, if I've set the contents of a pouch for sale, and priced them, then my part of the trade is concluded. From there, another player should be able to buy an item at the set price without having to wait on my approval since I have already agreed to the price when I set up shop.
Naturally this doesn't stop people from bartering, ie if I set up shop and am chatting to friends while waiting for things to sell then there's nothing stopping someone sending me a tell and asking if they can trade something for a particular item I have for sale. There's also nothing stopping players putting an item on show that doesn't have a price associated so that buyers can make offers.
Basic summary of feedback : allow the possibility of player shops that do not require the seller to approve trades if a price has been set. It benefits the casual player, and improves the social aspect of the game as players find good locations to set up shop and compete for business.