It is obvious to me that no one is knowledgeable about this type of pot including the seller at $50 and the other one at $3000. I, also lacking the knowledge in this area, would pass.
Personally, I find Mexican pottery to be cheaply made and cheaply priced. This is through experience buying modern Mexican pottery. I do not know anything about old Mexican pottery but maybe it doesn't last long because it is so cheaply made.
This original old one from a gazillion years ago sold for $3200...
http://www.liveauctioneers.com/item/4940448If the $3000 one is authenticated from the same era, it is probably worth it but if not then the fake one on craigslist would be the better buy. I just wouldn't expect it to last for years though. Ashes to ashes and dust to dust, fake Mexican pottery is a bust.
