The recession may have cost you a job or put your retirement plans on hold, but there may be a gold mine in your attic.

Online resellers such as eBay(Stock Quote: EBAY) turned second-hand chic into a multi-billion dollar industry 12 years ago but, the resale revolution is not only on the Internet. More than 2 million people a year show up for signature collector’s events such as the Brimfield Antique and Flea Market Show, in Brimfield, Mass., where buyers and sellers trade vintage clothes, comic books and more.

“This place turns into ‘Tent City’ in the summer,” says William Simonic, a spokesman for the Brimfield show. “You can see people selling art, glass, lamps and period furniture all the way down Route 20.”

There are an estimated 200 million “collectors” in the US today according to the National Association of Collecting Clubs. This number includes professional dealers and regular people who collect antique coins, stamps, dolls and even cars as a hobby.  As you can imagine, the price tags can get large.

Here is a short list of some top sellers:

Item: A mint-condition issue of Amazing Fantasy #15, introducing Spider Man
Price: $227,000

Item: A pair of Mickey and Minnie Mouse dolls from the 1930’s
Price: $151,537

Item: The Honus Wagner T206 Baseball Card
Price: $2,800

If you’ve been living in a home for a few years, chances are that you’ve stashed quite a few clothes, old toys and maybe even a family heirloom or two in the attic. However, just because you have something old around the house doesn’t mean always mean that you’ll make money selling it.

Some items such as vintage metal toys, books and antique furniture tend to do very well with collectors. Though an item’s value usually goes up with age, the $15,000 price tag on a 1960’s-era recording of reggae legend Bob Marley singing doo-wop hits shows that collectibles don’t always have to be older than you are in order to sell.

“Everything has value to somebody,” says Larry Krug, founder of the National Association of Collecting Clubs, himself an avid collector of antique political buttons. “But, serious collectors are always going to be on the lookout for something rare.”

People will pay big bucks to stroll down “memory lane,” but there are a few things that you should do before you try to sell off a piece of your past:

Explore the market. You may still have a soft spot for that old teddy bear of yours, but that doesn’t mean that anyone else will pick it up. Do some research online or at the library to find out the value of an item.

Get an appraisal. Most people won’t find a Picasso stashed away in the basement, but if you think you’re sitting on something special, find an expert who can give you an honest valuation of the item. You can also contact local antiques and collectible clubs and organizations for recommendations. You can even take a picture of the item and send it to Sotheby’s or Christie’s. If they think it’s worth anything, they’ll tell you. Who knows? You may have your hands on a genuine piece of history.

Show it off. Collectors live for rare finds, so don’t be afraid to take an item on tour. Chances are if you’re excited about an item, someone else will be too.

You don’t have to sell. Only you can decide whether your heirloom is truly a cash cow or simply a reminder of someone dear to you. If you’re skittish about parting with an item and don’t really need the money, then don’t sell. You can always sell it later, and chances are its value will have appreciated.