Even with the server market there appears to still be a demand for player-operated shops on the server. I've had some good experience with a specific plugin for Bukkit called ChestShop.
http://dev.bukkit.org/bukkit-mods/chestshop/
This very simple plugin allows players to create shops with just a sign and a chest. It links in beautifully with most economy plugins and even has the ability to function seamlessly with LWC and LogBlock. There virtually is no database overhead because the plugin just reads the signs and links to the nearby chest.
It also has really easy permission nodes so it's a really simple addition to the permission system;
ChestShop.shop.create.* - create all types of shops
ChestShop.shop.buy - buy any item from shop
ChestShop.shop.sell - sell any item to shop
ChestShop.mod - open any shop chest, destroy stores
ChestShop.admin - open any shop chest, destroy stores, create admin shops
http://dev.bukkit.org/bukkit-mods/chestshop/
This very simple plugin allows players to create shops with just a sign and a chest. It links in beautifully with most economy plugins and even has the ability to function seamlessly with LWC and LogBlock. There virtually is no database overhead because the plugin just reads the signs and links to the nearby chest.
It also has really easy permission nodes so it's a really simple addition to the permission system;
ChestShop.shop.create.* - create all types of shops
ChestShop.shop.buy - buy any item from shop
ChestShop.shop.sell - sell any item to shop
ChestShop.mod - open any shop chest, destroy stores
ChestShop.admin - open any shop chest, destroy stores, create admin shops



