Defanged, cuddly king cobra for cheap on craigslist...?
Highly unlikely. I'm thinking (and really hoping) that's someone's idea of a joke. That or it's mislabeled as part of a scam.
To add to the topic though - I do see a lot of rattlers for sale on my local craigslist. Seems like people just go out and catch them for a profit (I believe that's illegal here without a permit) What makes it so worrying is how they just advertise its' shock value, basically saying how awesome they look and that everyone will be impressed at how cool you are for catching one. They never mention buyer requirements such as age or experience either, just "first one to give me $100 gets a diamondback". The whole thing struck me as being aimed at young adults especially.
Scary is right!