I recommend you make a written window schedule. This is an inventory of each window, its type and its dimension. A schedule can be sent to local representatives and suppliers for bids. You will get much lower prices if you bid the entire schedule just as a contractor would. Any other way and you are just a retail customer.

When I bid these projects, I create a table with columns for item number, description, length, width, height, comment, unit price and extended price. Mail or provide your bid to local suppliers. The unstated message is that you are informed, buying in quantity and expect to get a builder’s price. DO NOT buy from non-local suppliers, big-box stores or the internet and expect to get good follow up service. Your local supplier, especially for high-end products, expects to deliver and service the installed product in the event of problems. Try it, you’ll like it!