Johnny Walker wandered through Spirit Halloween this week, making a mental list of the ghastly things he will buy to transform his east Orlando yard into a ghoulish amusement park.

"I go a little overboard on it," said Walker, who particularly liked a $200 wolf that gnaws on a severed human leg and spits water.

Retailers expect shoppers such as Walker to generate $8 billion in sales for Halloween, a 16 percent jump from 2011. The spending surge comes as the holiday grows in popularity and as Americans feel more comfortable about opening their wallets in the slowly improving economy, the National Retail Federation said.

Halloween also could bode well for the Christmas shopping season, although the federation predicts a more modest 4.1 percent increase for it this year. On the industry's list of holidays, Halloween ranks near the bottom, ahead only of St. Patrick's Day. Halloween generates about 1.4 percent of the sales that Christmas does.

Even so, more adults want to have fun on what traditionally has been a kids' holiday. To do so, they're buying increasingly sophisticated and expensive props and decor.

And just as Christmas seems to arrive earlier each year, so does Halloween, National Retail Federation spokeswoman Kathy Grannis said.

"I really think that Halloween has morphed into a monthlong celebration," Grannis said. "More people are capitalizing on the fact this is becoming a very popular holiday. I think it can only get bigger."

But even as some people say they'll spend more, many continue searching

for deals.

Walker, for example, uses coupons that he finds online. He also plans to wait until the last minute on Halloween to make some of his purchases, when stores slash their prices.

"I already got my vacation day in for that," said Walker, a bus driver.

Retailers are using all kinds of tricks to scare up business. Walmart offers free shipping for orders of at least $45 and has an expanded selection this year.

For the first time, it is allowing customers to try costumes on in stores, or they can use an online tool to model purchases before buying. Kmart has an online tool as well, which lets people mix and match items from the shelves to create a custom costume.

More consumers are turning to the Web for Halloween shopping, said Joyce Darch, who co-owns a couple of temporary Halloween Headquarters shops and a year-round party-supply store in Central Florida.

Several costumes, including Merida, the heroine from the movie "Brave," have sold out online. Though sales in stores are on par with last year's, Darch said, she has had double-digit increases through her website.

The improving economy has posed a challenge to so-called pop-up stores that appear just for the holiday. Darch said it has become a little tougher to find vacant spaces. The old Sound Advice near Florida Mall that Darch and her husband used to rent now contains a dollar store.

Still, another pop-up chain, Spirit Halloween, has opened more U.S. shops -- just short of 1,000 compared with about 970 last year, senior marketing and creative director Lisa Barr said.

Hot Halloween toys include a life-sized doll modeled after a little-girl-turned-zombie from "The Walking Dead" TV series. The animatronic figure, clad in a pink robe and clutching a teddy bear, sells for $159.99. Zombies are popular this year, thanks partly to the TV show, Barr said.

Meanwhile, Big Bird costumes have been strong sellers ever since Mitt Romney mentioned that he would cut off funding for the popular Muppet's public-television show during the first presidential debate. Masks of Romney and President Barack Obama have also been popular.