Any replacement window prices will vary by price. Bigger windows cost more as do specialized ones, like casement, odd shapes, etc. The easiest way to get an idea on cost is to go to one of the websites for one of the DIY warehouses and check out their prices. Of course that price will not include installation but the warehouse can quote you prices for that. Most of the windows sold today by reputable companies are double glazed and energy efficient.
There is a provision in the tax code for a credit for the change over but there are a few caveats to qualify.
For a quality replacement window you can expect to pay on average between $600-$1000 depending upon a number of different factors, but one word of caution, do not be fooled on the $189 window as it is a common bait and switch technique because the price will be almost double this and in most cases the window is not well-made.
Definitely look into the tax credit – here is the website to find out the information you will need:
Before proceeding with your purchase I also recommend that you take a look at this free resource on replacement windows: