Example Multi-Vendor From Lua

NPC_ID =  --NPC Entry ID Goes Here

function OnGossipHello(event, plr, obj)
    plr:GossipClearMenu()
    plr:GossipMenuAddItem(0, "Menu 1", 1, 1)
    plr:GossipMenuAddItem(0, "Menu 2", 1, 2)
    plr:GossipMenuAddItem(0, "Menu 3", 1, 3)
    plr:GossipMenuAddItem(0, "Menu 4", 1, 4)
    plr:GossipMenuAddItem(0, "Menu 5", 1, 5)
    plr:GossipMenuAddItem(0, "[Exit]", 0, 999)
    plr:GossipSendMenu(1, obj)
end


--plr:SendVendorWindow(obj, 0) Place NPC ID Where = 0

function OnGossipSelect(event, plr, obj, sender, id, code)
    if (id == 1) then
        plr:SendListInventory(obj, 0)
    end

    if (id == 2) then
        plr:SendListInventory(obj, 0)
    end

    if (id == 3) then
        plr:SendListInventory(obj, 0)
    end

    if (id == 4) then
        plr:SendListInventory(obj, 0)
    end

    if (id == 5) then
        plr:SendListInventory(obj, 0)
    end
end

RegisterCreatureGossipEvent(NPC_ID, 1, OnGossipHello)
RegisterCreatureGossipEvent(NPC_ID, 2, OnGossipSelect)