Simple Showcase is a great shop plugin, it provide a lot of great features for all servers out there, but it's also very simple to use, for server administrators, and for players their self.
With Simple Showcase you can create 'server owned' and 'player owned' shops. With 'server owned' shops you can sell anything you want, not only regular Minecraft items, but also other products, even more if you install some 3th party plugins which provides more products to sell. With these shops you can do anything you want, you can set the product prices, you could set a custom permission node for each shop, you can set minimum and maximum quantities for each transaction, and you can even link the shop to an external price list to keep the shop prices up-to-date by making a change in the external file.
'Player owned' shops can provide even greater features, now players are able to create their very own shops to sell their own stuff to others, by using a command, placing down a block and entering the price into the chat, and all of this is very simple to use, help commands are included.
With Simple Showcase you can even create booths in protected worlds to give players the ability to place their own shop ...
... on one of these. If you want to, you are able to set a 'Claim Price' for a booth so players need to pay a little when they want to claim a booth. Simple Showcase has support for almost all of the major Permissions systems and Economy systems available out there. Build-in help commands are available to help you out of your problems.
Simple Showcase does also provide API support, this will give other developers the ability to sell anything they want through the shops. Developers could also get fully control over all of the shops. There will be a lot of plugins available out there which you could install to get even more features available.
Simple Showcase is a must have for most servers!