I do not buy my cats treats very often, but when I do, I want them to be not only yummy but also good for the cats, health-wise. That's why I had picked Special Kitty Tartar Control Cat Treats that are said to help clean the cat's teeth. One 4.5 oz bag of these treats was a little under $2. I chose tuna and salmon flavor, thinking that it would be an instant hit with my cats who normally love fish. However, only one of the two had reacted the way I thought, he started begging for the treats as soon as I'd let him smell them and then crunched them up with great pleasure. The other cat showed no interest. Each time I served the treats, I would try to persuade him, and he'd only eat a couple of pieces, just to be polite.
My bag lasted for several weeks, since you should only give a limited amount per day, depending on the cat's weight (the directions are printed on the back of the bag). I do not know whether the treats helped to remove tartar as it is not something I can verify; my cats seemed to have healthy teeth, and I wanted them to stay healthy. So I guess it is more of a matter of my own peace of mind - knowing that I am doing something that is good for my cats.