Halloween brings treats for everyone. But if you're not careful, you'll find a big trick in November's credit card bill.

With the Christmas holiday gift-giving season fast approaching, you might not think of Halloween as being particularly significant. As it turns out, however, Halloween means big business for retailers.

Shelling out for everything
According to the National Retail Federation, Halloween sales are expected to top $5 billion for the first time this year. Among those the NRF surveyed, shoppers plan to spend an average of over $64 for the October holiday.

While candy is a perennial Halloween favorite, people actually spend more on costumes -- an average of $23, versus just under $20 for candy. Add in another $18 or so for decorations, and you're quickly talking about money that deserves its own line item in your budget.

Frightened candymakers?
Another threat to treat-sellers: the health craze. Hershey (NYSE:HSY), which has suffered from a loss of shareholder trust and bittersweet earnings shortfalls, is having to adjust to consumers who are more concerned about obesity. Campbell's Soup (NYSE:CPB) recently decided to slim down its business by selling its Godiva chocolate unit. Cadbury Schweppes (NYSE:CSG) is splitting its candy business from its beverage unit and is trying to improve profitability through acquisitions. And as Business Week noted a while ago, candy sales in the past year for Christmas, Valentine's Day, and Easter were all down. Will Halloween sales follow suit?

As long as kids go door to door in neighborhoods, candy is likely to stay popular. Even if people are buying healthy for themselves, no self-respecting homeowner is going to take the chance of giving out yogurt-covered fruit bars for Halloween. All you have to do is think back to what happens to houses where kids got bad treats.

The view from the dental chair
From seeing the results of all that sugar, doctors and dentists have strong opinions about Halloween. Some suggest feeding your kids a big meal before going out trick-or-treating in order to forestall the brunt of gorging candy. Others say those taffy apples and hard candy are OK as long as you have good dental hygiene. And at least one column takes the practical approach, saying it's better to let kids get their sugar binge out of their system all at once than to let them get into the habit of having a piece or two of candy every day.

No matter how you decide to celebrate Halloween, keep an eye on your wallet. As challenging as it is to keep holiday shopping under control, the last thing you want to do is to start out on the wrong foot. Figure out what you can really afford to spend and then stick to your budget. That way, you'll make sure that your Halloween treats don't turn into a tricky financial crisis.

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Fool contributor Dan Caplinger loves Canadian chocolate bars but hasn't come up with a good costume idea in years. He doesn't own shares of the companies mentioned in this article. The Fool's disclosure policy respects the law.