When you say.. "an outside piece of glass".. you really need to give a bit more information.
Is it single glazed ... or double glazed. ?
Is it in a window, or in a door. ?
Is the door or window, wooden or plastic.?
Is it on the ground floor..?
If it's a door, the replacement pane will need to be toughened or laminated. All these little details add up.
It is'nt just a piece of glass..!