We had Philip and his crew of two clean carpeting on two floors and two full sets of stairs prior to our moving in to our house. He was a very nice guy to deal with. We weren't able to get him into the house prior to the work, so he gave us a 'worst case' estimate based on the condition of the carpet and the time they'd have to spend.
The results were that the carpets were as clean as they could be (previous owners had left some uncleanable spots), and they did hit this 'upset' limit cost, though it's entirely possible that they spent a lot of time trying to get some of these stains out. I'm not sure if the cost was low or high relative to other companies, but I'm guessing it was probably comparable to the average cost. I did call one larger company and they quoted me almost $900 for the same area, so I guess we paid a pretty reasonable price.