[noloqy]

I've abandoned purchases as well. When I know I might be missing out on a coupon, I go hunt for it. Most of the time I don't find the coupon I'm looking for, but I do stumble across (coupons for) other products, which might offer a better deal. I end up purchasing those, or not purchasing anything anymore.

Instinctively I agree with the author: when a customer has effectively made a purchase decision, a webshop shouldn't divert him to random pages on the internet, unless there is a mechanism in place that leads to extra sales. Showing a coupon box during one of the final phases of the purchasing process is a way of diverting customers to random pages on the internet.