Here’s a comrade-in-arms in the world of Psychology of Information Technology: Dr. Jamie Madigan of The Psychology of Video Games blog.
His latest post The Psychology of Video Games | The Psychology Behind Steam’s Summer Sale tells us the exact behavioral cues and common human pitfalls that Steam (a downloadable video game retailer) utilizes to get more of your money. Even if you aren’t a gamer, go take a look at the article. Lots of research there.
Being aware of tricks retailers play to prey upon your wallet helps you become less of a victim.