ModuleShop

This is a basic shop add-on. You will need to find a way to update the signs when they are not valid but maybe a existing packet might do it. Giving the player an item is not efficient(Could lead to maybe someone stealing it but haven't tested it). Also you might want to add a ID checker in case ID does not exist. At the moment these signs can hold infinite stock, adding a chest shop will fix this. If you want I can write it and pull request again.