they range in price from about 50 to 5,000 dollars. a cheaper model will do the trick but its often worth paying more for a mid to high-range model, as technological advances in recent years have equipped some with extra capabilities such as trans-sexual detection (handy in dark clubs and asian countries), metro-sexual detection, (handy if you are blind but still have standards), bi-sexuality detection (always good to know) and even bi-curious detection.

i don't know where you live but here in Canada they are available at Future shops as well as Circuit City.