@v0dka
Masks cost more from approvedgasmasks.com because they sell only new production, unexpired, unused masks, as opposed to just about everything else that is out there that is surplus. I have done business with them in the past and am satisfied.
@Walker
There's no real sense in getting into the specialized gear and filters unless your just swimming in money and have nothing better to spend it on. The whole argument about "I'm not going to bother with a gas mask that will protect me from things like volcanic ash, radioactive particles, the zombie flu virus, tear gas, etc.,... because it won't protect me from every possible type of chemical known to man" is getting old and counter productive. A good fitting mask with NBC filters will protect you in many situations (but not necessarily all) without breaking the bank.