[ajscherer]

"You learn that the average new customer brings in $50 in profit over their lifetime"

How do you know this figure is independent of your marketing efforts? If I start out paying $1 per customer, or people are just walking in off the street for free or whatever, and find those customers are worth $50, is it okay to just assume that the customers who cost me $20 to get through the door are also going to be worth $50?

I'd think the more it cost to get someone to do business at all, the lower the expectations for repeat business should be (interestingly, I'd think the same thing if I were a merchant considering doing a Groupon).