Maybe the OP has a quote on a higher quality carpet which would explain the higher price. When it comes to carpeting, I say to get the better grade. It will hold up longer and be cheaper in the long run because it won't look "worn" so soon and will last longer. In our first home, we had the builder-grade carpeting and it was awful after about 4 years. When we bought our current house, we went to the carpet contractor and asked for an upgrade at our expense. He showed us his "builder upgrade" which was still bad, IMO. I kept telling him we wanted better stuff or we'd take a credit on the carpeting and have it put in by someone else. After looking at several grades, we ended up buying a better carpet, and we paid an additional 2800 OOP in addition to what the builder price was. It's been over 8 years now and the carpet is still fabulous! It has survived 2 kids, a hubby who doesn't remove his shoes w/out prompting, and 3 dogs. When I get it professionally cleaned, the cleaners usually comment on what a great grade of carpeting we have.
Rule of thumb when purchasing carpeting -- When you bend the carpet square, if you can see the plastic grading through the carpet, the carpet is not great quality and will crush faster.