Shopkeepers is a Bukkit/Spigot plugin for Minecraft severs that allows you to set up custom villager shopkeepers that sell exactly what you want them to sell and for what price. You can set up admin shops, which have infinite supply, and you can also set up player shops, which pull supply from a container.
On this Discord server and can find discussions and news about the Shopkeepers Bukkit plugin, ask other users for help with plugin-related issues, or, if you already have some experience with the plugin, help other users with their issues or offer ideas on how to achieve certain tasks.