My Users Say "No Thanks" to Free Money?
blog.foundrs.com
blog.foundrs.com
Would I share something useful/cool with my friends for free? Yes.
Would I bother to prove I had shared with my friends for $2? Probably not.
Overall, what everyone is telling you (here and in the comments on your blog post) is that putting links and/or endorsements on a social networking service is much more than just a fee-for-service proposition; there are other intangible qualities that are important, primary among them what your friends on these social networking services think of you. You want to believe that your friends post links to things because they're good, not because they're getting a discount. In fact I'd argue that one of the main reasons people like social media in the first place is that it's a person-to-person interaction that's not commerical in nature.
When someone has their hard-earned money out and is about to pay, they are cautious. They have made sure that they have gathered exactly what it is they want to purchase. They know that virtually anything out of the cashier's mouth or anything appearing on the checkout page that isn't "thanks, come again!" is likely to be something that's going to take time to do, cost them money, cause them to lose some of their privacy, receive junk mail, spam their friends, etc.
He'd probably be better off simply putting a message on the "transaction completed" screen simply asking them if they could do whatever it is he wants them to do.
The other possibility is that you didn't have enough users to convert any.
To me, spamming people that chose to listen to me on whatever site or medium seems like an egregious violation of trust. If I link to or recommend something, I want that to be meaningful.
I'll do it gladly if I like your product, but not because you've bought me for a couple cents.
On second thought, your $2 discount is very small too. Maybe if you discounted 50% it would work.