With experience in managing projects, I have a broad knowledge of Pricing & Time frames for Materials, Labour and Delivery.
I've provided examples of a quick quotes for Homeowners.
Notice how the increase in price is only a few hundred dollars per room? Often, Tradies charge large margins on their materials.
I personally don't see the advantage for either party in working this way.
With a fair quote based on initial cost + increase of time and materials, it is easy to find ways to lower the final pricing, whilst still delivering to the highest standard.