Homemade costumes and trick-or-treating? That's for amateurs.

Halloween has morphed into an all-out spending spree, as the business of fear has grown into a multibillion-dollar industry. The nation's largest retail trade association projects that would-be ghosts, zombies and vampires will spend a record $8 billion this year. But it's still a far cry from the December holiday season in which consumers spend more than $500 billion.

Derwood resident Denny Carter, though, says Halloween is his most expensive holiday. He estimates his total Halloween tab will surpass $1,300 -- with the majority of that going toward his annual Halloween party. Carter, 29, is also one of many adults who makes going to a haunted attraction an annual tradition.

Paying ... and paying
  Adult admission Included activities Activities with additional cost Additional fees
Montpelier Farms $10 corn maze, hay rides, animals duck races, scarecrow workshop, barrel train $3-$8
Cox Farms $17 prime/$14 regular giant slides, apple cider, corn maze bonfire, Fields of Fear up to $19
The Warehouse: Project 4.1 $29.99 haunted warehouse souvenir shop n/a
Markoff's Haunted Forest $25 haunted forest hayride $17
Field of Screams $20 Trail of Terror Lusion Manor, hayride, paintball $15-$18

At Markoff's Haunted Forest in Poolesville, Carter spent $110 on himself and his wife for the entry and additional hayride fee. But, he says, it's worth it.

"Unless the prices really skyrocket on all these things I like to do, I won't change activities," Carter said. "As much as I complain, it's like a football fan complaining about the price of ticket. It's just something you pay for."

Some area spook-seekers have learned ways to have seasonal fun at a reduced rate, relying on coupons and visiting farms on off-peak days to save money. Spike Silvernail, of Bristol, said he and his family of six went to Cox Farms in Centreville on $9 admission tickets last week.

"We've gone on a weekend before and paid the high-dollar ticket, and it was super-crowded," he said. "We know enough now not to go on those days."

The Washington region features more than a dozen farms and haunted attractions that draw more than 100,000 visitors every October, making Halloween the driving force behind their annual business.

The average consumer this year is expected to spend almost $80 on candy, costumes and cards alone, according to the National Retail Federation. But factoring in other activities like haunted houses and other seasonal attractions, total Halloween spending will hit a frightening $8 billion in the U.S. this year, the federation said.

"Halloween has morphed into a monthlong celebration of the fall," said federation spokeswoman Kathy Grannis. "The growth in popularity ... has only recently begun to get the attention of companies who may not have inserted themselves into the conversation before."

One in four adults said they planned to go to a haunted attraction this year, according to the retail federation. At $20 to $30 a head, the more successful businesses can rake in enough during a one-month period to get owners through the year.

Justin Watson, co-owner of Hallow Inc., which opened a $30 general admission haunted attraction in Rockville this year, said his group expects to make enough money in 23 nights of the Warehouse: Project 4.1 to sustain them until next Halloween. And if the business hits its targets, Hallow Inc. plans to expand to other cities over the next five years.

Watson said the co-owners got the idea after going through another haunted attraction.

"We saw the lines ... and we thought these people are making money hand over fist," Watson said.

The region's shrinking agricultural industry has also found a new cash cow in Halloween and the fall season.

Cox Farms gets about three-quarters of its annual visitors during its five-weeklong fall festival, according to marketing manager Ryan Mauter. The festival features a slew of activities -- including some attractions for an additional fee -- and in peak season, as many as 13,000 people pay the $17 admission over a single weekend.

In Upper Marlboro, Montpelier Farms' admission is $10, and some activities, like making your own scarecrow, cost up to $8 more. Shelby Watson, the farm's events coordinator, said 25,000 of the farm's 30,000 annual visitors last year came during the fall. And 2011 was a down year.

"This year, we've almost doubled our weekend attendance," she said. "If we continue, we're on track to double overall."