Some of us have smart shopping-OCD. We're so obsessed with getting a bargain that we undervalue our time, and will spend 20 minutes to save 20 cents. That I suffer from the illness became obvious to me when I tested the patience of some friends while I compared unit prices on sugar free iced tea mixes at the grocery store.

I'm not alone, however. Jean Chatzky, recently wrote that she spent a full workweek trying to save a few hundred dollars on a new television. Chatzky offers a wonderful formula for estimating the value of your time, and deciding whether comparison shopping for Tic Tacs is worth doing:

Say you make $100,000 a year. Remove the last three zeros ($100), divide the number in half and you get your approximate hourly rate, in this case $50. Unless you're "making" that much by shopping for your TV or constantly combing the Internet for slightly higher CD yields (or whatever your time-suck happens to be), you're losing money.

Here on WalletPop, we love offering money-saving tips but it's important to keep this in mind: Depending on your financial situation, some of these tips may be too petty to be worth your time. Being a "smart shopper" may actually be costing you money!