# of squares = square footage / 100 ft^2 * 3 squares
Take the cost of the shingles and multiply by 3. That might be on the high side but will give you a working estimate.
Mine is about to cost $10,000. I have no idea how much yours would cost, because I don't know how big it is, what kind of roofing is being used, what the local price for that type of roofing is, whether a roofer is being hired and what roofers charge where you are, or if someone is going to DIY it. Answer all those and we might be able to get close.
