Need a kitchen table, a road bike or an acoustic guitar? You could browse the big box stores and shell out the cash for a new model. Or, you could hop on Craigslist.

Since its launch about 16 years ago, Craigslist.org has become a more popular place to buy and sell items online than even eBay -- thanks to its ease of use and the fact that anyone can list or browse items on the site for free.
For those who may be unfamiliar, Craigslist is essentially an online version of a 'classifieds' page you'd find in your local newspaper.
In recent years, the site has stirred up some controversy, ranging from illicit posts in a now defunct 'adult's only' section to criminals using the site to find victims. But it should be known that Craigslist is more than crazy online flea market full of 'rants and raves' and scams. The site can save you some serious money -- not to mention time and gas spent shopping -- if you know what to look for.
Of course, there are some things you don't want to buy used. Here's a guide to what's worth scoring on Craigslist, and what's better with a new price tag.

What to Buy on Craigslist

Furniture and Appliances
People remodel, redecorate and change their minds all the time. And naturally, when they do, in goes the new furniture and appliances and out goes the old.
Selling large items on a paid site like eBay can costs loads in shipping, so this is one category where sellers choose Craigslist hands down -- and that can land you a great deal.
And even if they're used, many of these items are built to last for over a decade, so you're likely to get many more years of use out of them. A friend of mine bought a combo washer/dryer for $75 from someone looking to lighten their load before a move.
A stipulation here is that you will likely need a vehicle that can haul away the furniture or appliance, so be sure to have something lined up before you start shopping.
Music Equipment
Musicians (guitar and keyboard players especially) are always looking for the newest piece of gear.
But because musicians don't always have a lot of cash lying around to buy what they consider better equipment, many are willing to sell old equipment for quick cash -- making Craigslist the perfect place for buyers to get music gear for pennies on the dollar.
You can also score real deals on instruments and music equipment from beginners who lost interest in their new hobby. In the same vein, if you're a beginner, why spend the money on a brand new instrument?
Exercise Equipment
According to the National Sporting Goods Association, Americans spent $5.4 billion in 2010 on exercise equipment. Of that, I would venture to say about half of it is collecting dust, used for hanging clothes or on Craigslist.
That's not the most scientific guess, but spend a few minutes on Craigslist and you'll see what I mean. There's an abundance of new and gently used exercise equipment at a fraction of the original price.
I found a gently used Bowflex Classic Home Gym -- normally priced at $650 -- for just $200 on Craigslist, as well as more than a dozen gently used treadmills -- each of which would have sold for $1,000 or more a year ago -- for less than $400.
As with anything on Craigslist, be sure to test the equipment to make sure it works properly.

What Not To Buy on Craigslist

Collectibles You Know Nothing About

It sure can be tempting to pick up that antique chair for $25 bucks -- especially if you think it's the ultimate garage sale treasure! The only issue is, if you don't know anything about antiques, it's likely you are just getting an old chair that won't rise in value. This axiom extends to anything else collectable that you are ignorant of: beanie babies, trains, pottery, and whatever else that soothsayers are telling you will make you rich in a few short years.

Only buy antiques that you like for aesthetic reasons, rather than as a cross-my-fingers investment -- unless you really know about the antique you're getting.

Car Seats
You or someone you know may have a baby on the way and of course need to get them from place to place in a car -- but don't skimp on a car seat. You have no way of knowing the safety of a car seat you buy second hand. It may have been in a previous accident, which could have worn or damaged its vital working parts. Older seats, even if they weren't in an accident, may not have the required safety features included in the newer models.
Mattresses

Think of all the time you spend on a bed; 8 hours a day, or one-third of your life. A mattress is not a place to cut corners, no matter how badly you want to save money. There are untold ways that a previous owner could ruin a mattress. From bed bugs to 'spills,' it's just not worth getting a mattress used on Craigslist or otherwise. If a mattress is older than eight years old, it's already past its useful life.

The Investing Answer: Buying used items on Craigslist can be smart and save a lot of money if you know the right items to buy. As a rule of thumb, steer clear of wearable or form fitting items that are used -- as they can be unsafe or a health-hazard. Durable goods that last longer than one or two years, however, can be real bargains.