QUOTE (Gas Giant @ Nov 12 2008, 10:57 PM)

The good ones that measure adjustable rentgen rates have a nearly impossible to find 400V battery.
Use a modern lithium-ion battery pack at ~24V and a 400V DC-DC converter. I'm not sure about cost, but I know you could get better lifetime out of a newer battery technology. Even a new lead acid with a step up converter will outperform those old batteries.
Anyway if you really want to buy a new one, I know that the ones made by ludlum instruments (http://www.ludlums.com/) work well.
Also as somebody else mentioned, alpha radiation is pretty much only dangerous if you ingest the source. Beta is also relatively benign as it won't penetrate a car very effectively. Gamma rays are the scary shit, they fry you and are a bitch to stop.
I can't argue with the usefulness of a geiger counter / survey meter though. If you are hiding in a fallout shelter, it would be helpful to have some idea of the levels outside when deciding if you should stay holed up another week even though you are out of food. Also when fleeing a contaminated area it would be helpful to know you aren't just driving into the fallout of a different area.
Unless you are certain you can escape the fallout area or absolutely can't find a basement to hide in you are better holing up in a deep basement for at least a month to let the worst shit dissipate. Potassium Iodide (KI) pills are also a lifesaver, if you don't have access you can spread tincture of iodine on your skin. This iodine saturates your thyroid gland so it will not absorb I-131, a major component of nuclear fallout.