saving moneyOne of my latest bargain finds is batteries at my local dollar store. I’ve been buying packs of eight AA and AAA batteries for—you guessed it—$1. That’s a huge savings compared to the $8 per eight-pack at my local grocer.

However, I’m starting to wonder if the dollar store batteries are wearing out more quickly than usual. If that’s true, I’m not getting as good a deal as I thought. Even if I spend less up front, I may have to buy the batteries more often. Plus, I’m adding more disposable batteries to the landfill, and I don’t like that idea.

You’ve probably faced this kind of purchase before and wondered: Is this bargain really a good deal? Here are some situations in which it might not be:

It’s so cheap that it doesn’t last.

My dollar-store batteries may be an example of this. Or the trendy outfit you bought from a discount retailer that immediately starts to fray at the hem. Or the off-brand musical instrument for your child that breaks down before its time. When you buy something so cheap that you have to replace it, you spend more. This is one reason I’ve started thinking about when it makes sense to buy what you might call “heirloom” purchases—items upon which you spend a little more money up front but keep for a long, long time. Blogger Carl Richards explains this idea really well. 

It’s not something you wanted or needed.

You may have been suckered in by the price. You went into a store to buy one T-shirt, but the sign said, “Buy one, get one half off.” Who can resist that bargain? In truth, you didn’t need the second T-shirt—and you just paid 50 percent more than you originally planned. Definitely not a deal.

It creates clutter.

Yes, that mug was free at the conference, but how many company-logo coffee cups do you need or use? Ditto for clothes that are so current that they will be out of style next year and you won’t wear them. You’re just filling your closet with laundry.

It can be inaccurately compared to something more expensive.

This concept is called “price anchoring,” and it often trips us up. You know how baby ducklings have been known to imprint themselves on the first living being they see when they hatch? We do the same when it comes to prices. If the first TV you consider while shopping is $1,500, your brain will anchor on that and decide it’s an average price. If you then find a similar TV for $1,200, you may decide it’s a great deal—even if both TVs are extremely overpriced!

It was found with similar products on a grocer end cap.

You’ve probably seen something like this: A name-brand pasta, sauce, drink, and packaged dessert for a special price. However, in many cases, you could spend less by buying cheaper brands of each item—as well as by skipping the food items you didn’t intend to buy (like the dessert).

It’s a menu special.

There’s quite a science behind how restaurant menus are created. Marketing experts say the all-inclusive “fixed price” special is often not really a deal. You’d be better off ordering items separately.

It’s offered by a questionable seller.

Scamsters—particularly those selling items online—want to offer you a deal so good you can’t pass it up. If the seller’s price is significantly lower than anything you’ve seen, be extremely wary. On an online site, check out the seller’s rating. Ideally, you should only buy from sellers who have a 99 percent or better positive rating and who have completed lots of sales. On sites like Craigslist, be sure check fraud warnings.

When have you found that a deal is not really a deal? Share your shopping tips in the comments below.

Teri Cettina is a personal finance and parenting writer/blogger. Prior to becoming a freelancer, she was an employee communications writer and editor for a large regional bank. Follow her on Twitter: @TeriCettina