What is your square footage of carpeting, OP? It's hard to judge on if you got a fair deal just based on number of rooms. Also, the more cuts that have to be made (around corners, etc..), the more you'll pay because the rest of the carpet that gets cut off ends up being scrap, but you still have to pay for it.
The price you got doesn't sound unreasonable for a really good grade of carpet. When we had our home built 11 years ago, we opted not to take the builder's carpet or the builder's upgrade (been there, done that in the past and even the upgrade was very poor quality). We went directly to the place that the builder contracted with, found out what they were paid by the builder for the carpeting, and made a deal with them to upgrade to one of their non-builder grade carpets where we paid the difference OOP. It's 11 years later and our carpets are still in really fabulous shape, minus a few places where our dogs tried to pull up the seams.
It really pays to have the best of the best carpet put in. My neighbor had the builder's carpet replaced 4 years after she had her house built (same time as us), but she got a cheap replacement and her now 7 year old carpeting is already in dire need of replacement again while our 11 year old carpet still looks great.
One last thing... To increase the life of your carpet, don't wear shoes in the house and NEVER EVER have your carpets cleaned with any carpet cleaning products that contain soap.