joke

someone told me a joke: there was a market that sells brains. a man walked in and the seller introduced him to different brains and their prices. he showed the man a chinese brain and said it cost five dollars. the german brain was 10 dollars. the next brain was a few hundred dollars. the mexican brain was over 1000 dollars. the japanese brain was 4.50 dollars. the man was surprised and asked why? the seller replied: it's because the mexican brain is still new because it has never been used!