To install uPVC windows is not easy. You can do it yourself if you are an experienced do-it-yourselfer, but for the average home owner it is a task too difficult to attempt. Often when you purchase uPVC windows the dealer will offer an installation service as part of the price.
Typically a 6 sided uPVC bay window with top opening window can cost you $2,000. For $7,000 you can buy and get installed 10 uPVC windows and 2 doors. Obviously the bigger your purchase the greater the discount you can get on individual items and the cost of installation.
This may seem like a lot of money. But you must consider the money you will save.