It will be the financial death of me.
Super-saver shipping, I can't resist you. Even though I really just wanted those two books, totaling $19.95, for a mere $5.05 more, I don't have to pay any shipping at all! It's practically getting something else for free, because I would easily pay that much to have the books shipped. But nothing actually costs $5, everything is at least $10 or more, not to mention that I've now bought two books and am feeling very intellectual, so really I should get a CD, right? So now I've spent $32 with taxes, $12.05 more than I originally planned on.
And I will probably do it again next paycheck. What's the definition of addiction? Oh wait, here it is: "to devote or surrender (oneself) to something habitually or obsessively"...that pretty much wraps it up.