That does suck you got ripped off, but does no one else take some preventitive measures to make sure it doesn't happen?

First off, don't EVER give a dealer your money until you've seen your bag weighed out in front of you. Anyone that doesn't do that is most likely some amatuer small-time kid. Then once you see it weighs out, you hand them the money. Not before. I know it's hard to sometimes, but if you want your money's worth, you gotta do it. And yes, that might mean getting a new dealer and not smoking as often, but at least you didn't pay 40$ e'ffin dollars for a gram!