@LBrinkmann,
I read this and couldn't find a way to shorten it (my speciality! lol). In fact, I would even add a word - "the" insurance allowance. It's not necessary, but I would add it.
Another way would be (although it's more awkward): Attached is a change order for material upgrades for customer-selected vanities and faucets above the insurance allowance of $100.00.