RuneScript

[proc,npc_talk]
if_close;
npc_say("Hello adventurer! Welcome to my shop.");
~chatplayer_say("What do you have for sale?");
npc_say("I sell a variety of potions and magical items.");

[clientscript,shop_interface](int $interface)
if_setsize(0, 0, 200, 300, ^setsize_abs, ^setposh_abs_centre, ^setposv_abs_centre, $interface);
if_settext("Shop Inventory", $interface);
cc_create($interface, ^iftype_text, 0);
cc_setsize(0, 20, 200, 0, ^setsize_abs, ^setsize_abs);
cc_settext("Available Items:");

[queue,process_purchase](int $item, int $amount)
if (inv_total(inv, $item) < $amount) {
    mes("You don't have enough coins.");
    return;
}
inv_del(inv, $item, $amount);
mes("Purchase complete!");