Hey TC,
There are several different types of meteorites. Some are metallic (nickel-iron), and some are rock. The rock ones are typically not "HOT" (meaning a metal detector won't pick them up). The nickel-iron ones sing like a bird. The metallic meteorites are quite valuable.
A lot of the valuable iron meteorites' value is determined by not only it's content, but it's shape.
There are some useful websites about the subject.
Best,
Mike