The author of “Shoptimism’s” buying habits are irrational and wildly inconsistent.

Question: What has been your biggest spending mistake?

Lee Eisenberg: I make the same spending mistake over and over again, and it's a very inconsistent thing. I will go to a fair amount of trouble to do research on the most meaningless and inexpensive things: a USB cable or 12 AAA batteries; I mean, all these things that are not going to ruin my family's finances one way or another. I'll actually research those. But then I will be totally and erratically spontaneous when it comes to booking a vacation or a dinner or, you know, something that's expensive, without doing a whole lot of due diligence. And I make that spending mistake over and over again, to the point at least that, you know, I haven't broken the family's piggybank, but from time to time I test it. Having said that, I think I'm not a profligate buyer; I think I'm a fairly typical buyer in that I am given to irrationality and wildly inconsistent.

Recorded on November 9, 2009