[thom4782]

You're entitled to the value of your top before the glass broke. They can either replace your top with an equivalent used one or you'll likely be liable for the incremental cost between the new top's value and the old top.

This rationale is the reason why you don't get a new car when your car is totaled in an accident. The negligent party only owes you what the value of your car was before it was damaged.