Just Make sure you get these items and you will be ok.
Fusion Welded Frames and Sashes
So all fusion welded sash windows are the same? Stack welding is the same as an old single point weld? All manufacturers welds are the same? Really?
double Low-e coating
Would you recommend she get triple or double coat in the middle of the U.S?
What about the different spacers? Will she be OK with any spacer?
And make sure the installers are good and that they fill the gaps in the opening with a low density foam.
Wouldn't it be better for her to know if the installers are good before the job begins? Just because they use low density foam that means they are good? How about suggesting she call a few references before signing a contract?
You should be able to spend between 3 and 4 hundred per window.
So you are telling her she can get a top notch window installed' with LoE 366 glass for $3-$400? Good luck with that.
Find a local window and siding supply co., go to their show room view the different window mfg. they carry and they will recommend a good honest company they deal with to install them.
Or they might give her the name of an installer who is a drinking buddy, desperate for business and has offered to pay them a finders fee. How would a couple of clerks at a local supply house have any idea of the installers quality? If it was a Crestline distributor, do you think he would recommend Gorell or Simonton?