Get Some Bids
Getting at least three bids on your project is the most important first step you should take. There are so many variables that will increase or decrease the per window price that it is nearly impossible to know the fair market price when you start your research. So three independent bids should provide enough project details and pricing to get an accurate idea of the project requirements - four or five bids is better, but it can feel like a grind by the time the 5th one shows up.