If you have standard double hung windows it's a DIY project. My neighbor had a quote a while back of $25K for 18 standard windows that you could have bought at HD for under $300 a window, They are easy to replace and once you do one you can move pretty fast. I've done 4 houses by myself with and a helper. Check out the video on Lowes. I know there are plenty of high end windows but unless you plan on staying in the house forever and it's an expensive house there isn't a need to go crazy. DIY is the way to go.