M.P.
I have taken my carpets to Atiyeh's. (6'x 8') I ask for an estimate before I leave it. I've also had them clean my wall to wall carpeting and my sofa. I've always been pleased with their work.
The price will depend on the carpet's size, fiber content, and amount of soiling.
I have used cleaners who come to my home and the quality of work depends on the employee doing the work. These have been companies that advertised with coupons. The price is stated something like 3 rooms for $50. One time I was disatisfied and the company sent out a different worker. He cleaned the carpets again with no extra charge and I was pleased.
The second employee was exceptionally helpful. He went over the corner in which animals had been peeing several times as well as lifting the carpet and spraying a deoderizer on it. He also told me that using the spray rug cleaners from an aerosole can makes cleaning the carpet commercially more difficult because their solution mixes with the home spray and causes soil to stick to the carpet. Also that even when stains are not apparent after the carpet is cleaned there can be residue below the pile that works up to the surface. He went over my carpet 2-3 times in order to get it clean. Again there was no extra charge. This was several years ago.
I had my carpet cleaned another time by a similar company and sure enough they said they wouldn't clean it a second time because the stains do come back to the surface and that is just the way it is.
I recommend that you call several carpet cleaners and ask them for an estimate. They can give you a ball park estimate over the phone after they ask you several questions. Also ask them about stains that reappear in the next couple of days and how they would handle that. If you have pets ask what service they will provide for odor. Some companies will treat your carpet after cleaning it with a soil resistent spray. They do charge extra for that.
If the carpet is light colored and has several visible stains I'd recommend using an established service who will come out to look at it first. It will cost more but I found it worth the extra cost. I haven't used Atiyeh's in several years and so I can't responsibly recommend their company but if I were wanting to have a carpet cleaned I would talk with them first.
If you have Atiyeh's or another professional company of that caliber they will come out to look at your carpet and give you an estimate. They will also give you a reasonable assessment as to how your carpet or furniture will respond to their cleaning.