Creating a shop script

"on_start" = [

  money = 0
  pie = 0
  sword = 0
  treasure = 0
  ]

"level_trigger_1" = [ money = ( + $money 5 )

  echo "You got 5 moneys."
  ]

"level_trigger_2" = "showgui Shopkeeper"

newgui Shopkeeper [

  guitext "What're ya buyin, stranger?" chat
  guibar
  guilist [
     guibutton "Pie: 10 moneys" [
        if ( > $money 9 ) [
           money = ( - $money 10 )
           pie = ( + $pie 1 )
        ]
     ]
     guibar
     guibutton "Sword: 20 moneys" [
        if ( > $money 19 ) [
           money = ( - $money 20 )
           sword = ( + $sword 1 )
           ]
        ]
     guibar
     guibutton "Treasure: 40 moneys" [
        if ( > $money 39 ) [
           money = ( - $money 40 )
           treasure = ( + $treasure 1 )
           ]
        ]
  ]

]

newgui Inventory [ guibutton "Back" "cleargui 1" guibar guitext ( format "You have %1 moneys in your wallet." $money ) guitext ( format "You have %1 pies. Yum." $pie ) guitext ( format "You have %1 swords. Not that you can use them..." $sword ) guitext ( format "You have %1 treasures. Lucky you!" $treasure ) ]

newgui main [

  guilist [
     guilist [
        guibutton "Inventory" "showgui Inventory"
     ]
  ]
  guibar
  @main

]