Should I buy it new or used? For the truly frugal, the answer is most often used. Except for personal hygiene items and underwear, which should be purchased new, and things like computers and mattresses, which should be bought used only from someone we know and trust, everything else can and should be bought used. This makes sense from an economic standpoint, and also from an environmental standpoint. It fulfills the second tenet in “reduce, reuse, recycle”.
So, what is the best place to buy used? It depends on what you are looking for. There are always the big web-based sources, such as e-bay, Amazon and craigslist. There are large non-profits such as Goodwill. If your area has a Habitat for Humanity ReStore this is an excellent source of all kinds of things.
Then there are the flea markets, garage sales, and small local second hand stores. I believe it is best to start with the local sources first. The very best deals are generally at garage sales. Flea markets can be good if they are not over-run with cheap new goods, as is the case at some local markets. But, if the item is something that you might never see at a local source and you really need it, going to the web is still better than going to Macy’s, or even Walmart.
One of the best things about accepting second hand good is not having to pay at all. There are clothing exchanges, swap meets, and free-cycle groups in many places. If there are none near you maybe you can start one. This is one place the gift economy shines.
For big ticket items such as cars it is always better to buy used--but do your home work. The reason is that the car loses a third of its sticker price when the first owner drives it around the block. Even if you really want a new car, buying a late model low miles used car just makes sense.