Get Crafty!  
You absolutely do not have to buy a prepackaged costume for your kids. Last year, we took a clear plastic garbage bag, cut out a couple of holes at the bottom for legs, filled it with colorful balloons and my daughter went as a bag of jelly beans. She looked great. The year before that, my 12-year-old son pulled off a great Will Ferrell in Anchorman by taking a red blazer from my closet and putting on a cheap wig.

The National Retail Federation says the top three costumes this year are expected to be a princess, a pirate and Spider-Man—all things you can easily put together at home, says Amanda Formaro, founder of the crafts magazine FamilyCorner.com.

• A princess dress can easily be fashioned out of a little fabric from a discount retail store if you have even basic sewing skills, or you can even use hot glue since it will only be worn for a few hours. Then, just attach a piece of tulle to a cone hat made out of cardboard, and make a wand out of tinfoil.
  
  
• The pirate costume is equally easy and inexpensive if your kid has a striped shirt and a pair of black pants. Just add a bandanna, an eye patch made out of black fabric and a cardboard sword.
  
  
• And for Spider-Man, your best bet is the movie-themed pajamas, if you have them, or a little face paint on a red, long-sleeved T-shirt. "Whenever you're making a costume out of something that's just hanging around, it sparks your kids' creative sides and really makes it a lot more fun," says Pattie Donham-Wilkinson, craft expert for the Lifetime Network.