Ask HN: What results do you expect from Facebook or Google ads?

How much should I be paying for customer acquisition via facebook/google ads? What has been your experience with facebook vs google ads? Facebook approved my ad very quickly (within an hour?) and Im getting about a .045% click through rate at a cost of about $1/click. About 20% of the click throughs are registering. Still waiting for google to approve-- they are slow! 1) What kinds of conversions do you normally expect? 2) What is the cost of acquisition that I should expect? There is a quora thread which suggest $5-$6 and that under $10 is good.