I got mine done with trace elements, but I go through a nutritionist based in the uk - joy healey. 50 pounds for the test. It takes 2 weeks to come back. I don't buy the brands recommended on the hair test particularly, but take the advice on what to eat, avoid and bought other brands - mainly 'future formulations'.
Yes, its true the hair test isn't an exact measurement of minerals in your body. There is no test that can do that. Even blood tests only represent the amount in the blood. The hair test measures more: the ratios of minerals and how your body processes them. I personally think it is an excellent guide, but a guide only.