I hate Groupon. I'd be more impressed with their meteoric popularity if businesses were really benefitting. Instead, my favorite BYOB sushi place is overrun and I guarantee they don't retain all those Groupon customers.
Do you know they pay $5 to $10 per customer or is it a guess? just curious
In their early days, they were paying affiliates $2 per email submit.
Yes, they are definitely paying that much (or more). Groupon and Zynga are responsible for increasing the CAC via Facebook ads by 2-3x over the last year and a half.
This is yet another unappreciated benefit of having a business model where someone is actually paying for something. You get to pay to get users.