This post is from GRS staff writer Donna Freedman. Donna writes a personal finance column for MSN Money. She also writes about frugality, intentional living, and life in general at her own blog, Surviving And Thriving.

I’m currently house-sitting in Anchorage, where one of my duties will be kid-wrangling while my niece does the Alaska Run for Women. The first order of the day: Breakfast at IHOP, my treat — and at 8% less because I’ll be paying with a discounted gift card.

Sites like Plastic Jungle, ABC Gift Cards, Cardpool and Swapagift re-sell unwanted gift cards to hundreds of different retailers. A secondary-market aggregator called Gift Card Granny can help you find the deepest discounts.

Discounted gift cards are as good as coupons: They provide a consistent discount of 3% to 30% or more. While I don’t buy a whole lot of Stuff, I do use these cards to save money on haircuts, groceries, movies and more.

Where do they come from? Most often from someone who needs or wants the money more than the card. Since resale sites will pay up to 92% of face value, it’s an easy way to raise some fast cash.

But plenty of cards end up on the market because they were colossal fails. Maybe your well-meaning uncle thinks you’re as interested in fly-tying as he is. Or maybe you unwrapped $25 in plastic scrip to a shop where the cheapest item is $40. (Extra bummer points if it’s an item you don’t particularly want, or a store you’d never visit otherwise.)

Heck, I’ve even heard of a vegetarian being given a gift card to a steakhouse. True story.

A card for every buyer
Suppose you’re an independent-movie-house kind of person who never sets foot in chain restaurants? There’s probably a discounted card out there for you, too, such as:

  • Animal lovers: PetSmart, PetCo or 1-800-PetSupplies
  • Homeowners and DIYers: Lowe’s, Home Depot, Ikea, Sears
  • Tech fans: Apple, Best Buy, Dell, Radio Shack, Staples, Office Max, Office Depot
  • Travelers: American Airlines, hotels, Travelocity, BedAndBreakfast.com
  • Car owners: AutoZone, Pep Boys, gas cards
Tip: Some “cards” are actually e-codes, i.e., good only online. One woman I know accidentally bought a $50 e-code for Wal-Mart. So she shopped online for….a $50 Wal-Mart gift card.

Even if you’re on a super-tight budget and/or you prefer thrift shops and yard sales, chances are you hit “regular” stores once in a while for things like kids’ shoes, undergarments, OTC meds or school supplies. If so, discounted gift cards will take some of the sting out of paying retail.

Of course, if you’re OK with secondhand aspirin or yard-sale underpants you can just keep on keepin’ on.

How to get the best deal
I suggest going to Gift Card Granny to look for the deepest discounts. Note: If Cardpool is one of the best choices, you can sweeten the deal by purchasing through a cash-back shopping site called Mr. Rebates, which offers a 1% rebate for Cardpool purchases.

Don’t see what you want? Set an alert on Gift Card Granny and you’ll get an e-mail when the card becomes available. This is easy to do and also easy to cancel when (a) you get the card you need or (b) the e-mails start to get on your nerves.

Certain cards sell out fast – especially supermarkets and gas stations – so be ready to jump as soon as the alert hits your inbox.

Some sites offer additional services. I get “retailers of the week” e-mails from ABC Gift Cards, cluing me in about higher-than-usual discounts. Recently I helped a friend buy more than $300 worth of Lowe’s gift cards at 8% off, to pay for landscaping materials. A few days later Cardpool sent an e-mail touting 9% off Lowe’s cards for the next 48 hours. (Now they tell me!)

Tip: Keep cards from your favorite stores with you at all times, in case you see a hot deal or manager’s special.

There’s a subtle danger involved with the use of these cards: That the discount will tempt you into buying more cards than you need. Don’t buy anything that busts your budget. Even if it’s on sale.

Six uses for a discounted gift card

  1. End run around the wedding gift registry. If your BFF is registered at Bed Bath & Beyond and Macy’s, buy a discounted card and use it to pay for your present.
  2. Pump up PTA attendance. Offer a gift-card door prize at the next meeting. If you don’t see more parents there I’ll reimburse you for the cost of the card.(Just kidding!)
  3. Black Friday boost. Poised to grab $2 DVDs and $10 smartphones? They’ll be even cheaper if you pay with cut-rate cards.
  4. A gift in and of itself. If your brother loves a particular store, give him a card and let him buy whatever he wants. Buy it well in advance, though, because there’s a chance you’ll receive a seasonal or special-occasion card, e.g., a card decorated with holly or a wedding cake. (If so, take it to the store and buy a new card with it. If you don’t allow enough time to do that you’re going to look like either a re-gifter or the kind of cheap bastard who buys discounted gift cards. Neither epithet would bother me much, but you might have thinner skin.)
  5. Something for your kid’s teacher. Trust me: Ms. Smith absolutely, positively does not need another “No. 1 Teacher” mug. However, she might want something to put in the mugs she already has. I just saw Coffee Bean and Tea Leaf cards and Caribou Coffee cards for 10% and 12% off, respectively.
  6. Giveaway on your website. Nothing gets virtual butts in virtual seats like a giveaway. Put a gift card up for grabs and promote the heck out of your contest. No one has to know you didn’t pay full price. Unless, of course, your card has hearts and Cupids on it.

Treats for less
I brought along several other kinds of discount cards on this trip:

  • Red Robin, 8.9% off. Pricier than I’d like, but the fries and drinks are bottomless and it’s a family-friendly joint.
  • McDonald’s, 11% off. The play area is a good place to burn off kid-beast energy when it’s 45 degrees and raining sideways. (This has nothing to do with me and McNuggets. It’s totally, completely about the kids.)
  • Regal Cinemas, 15% off. Two words: Summer movies.
Tip: My daughter and son-in-law get free movie tickets and soft drinks at AMC through the My Coke Rewards program, then pay for their popcorn with a 20%-off AMC gift card. Yes, movie concessions are not frugal. But they’re fun, if you budget for them.

I don’t go to restaurants much. But I like to take my niece and her kids out to eat when I visit. So why not do it for 8% less?

Besides, this time around my food will be free. That’s because I have a social media relationship with IHOP, which just sent me a coupon for a free “Rooty Tooty Fresh ’n Fruity” breakfast. The downside? I have to speak the words “Rooty Tooty Fresh ’n Fruity” out loud. In public.

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