Any experience with replacement windows?

We need to replace about 6 windows including a bow window. I had a big regional company in to give us a quote (live in the Philadelphia area) and got the big high-pressure sales hype I was expecting. Their quote was about $13K which I thought was quite high. Of course they said that their windows were better than Anderson or Pella, etc., but for all vinyl windows??? So my question is what price should I expect for good double pane custom replacement windows, and can anybody recommend a company? I don't think the $3-$400 stock replacement windows from Lowes and Home Depot will fit because I'm replacing aluminum frame windows. Thanks -Reid