LivingSocial yesterday was selling $20 for $10, which is a good deal for everyone buying it (and remembering to then make use of their Amazon gift card). Not surprisingly, they sold at least 1 million for a total value of $20 million. Now if everyone who bought one of these were a new LivingSocial registered user, that would amount to a $10 customer acquisition cost. That’s of course a lower bound because there are likely to have been quite a few existing LivingSocial users and some fraction ...