You can open and purchase vaults from inside the GUI. Set custom prices in the config and configure the items along with messages shown in the GUI and the GUI itself. Requires PlayerVaultsX Plugin Link: https://www.spigotmc.org/resources/%EA%A7%81-%E2%96%AC%E2%96%AC%E2%96%AC%E2%98%85-playervaults-gui-%E2%98%85%E2%96%AC%E2%96%AC%E2%96%AC-%EA%A7%82.52057/