You go to a carpet supply outlet and pick out what you want. Than look for a independent carpet installer and have the installer quote you a price on the install.
I just did a total renovation on a two story apartment and doing the carpet and painting was out in my book . New bathroom and kitchen and wood flooring in the first level was as much as I wanted to chew.
The owner got hold of a independent installer and they told him if you get the carpet and pad there on location I'll give you a good price. The carpet guy told him exactly how he wanted to the carpet -two rolls 12 ft. wide ,he had about 12' by 28 ' plus the stair case to do.13 steps and a landing .
The owner bought the materials exception to the carpet tracks and I picked up the carpet and pad and my helper got it all up there on location. The owner saved a bundle really-just takes a little time on the phone and tenacity. The installers price was $300.00 plus his gas for truck -$320.00 total.
Carpet came from Lowe's about $ 600.00 maybe $500.00 on sale wt. pad. That's the other thing- look for sales on carpet. when they are not selling a lot they are hot to sell.That's when you find the best deals.
Carpet installation is either busy as hell or no work at all. Carpet cleaners same thing.
The installer drove 40 miles to do the job so he couldn't have had much of anything going on work wise at that time.
But that can always change over night. So the art of it is knowing when to close the deal .
If you want to sit back and have them do everything ,than yea it's gonna cost ya.