For most stores, December 24 is the busiest day of the year.

But for The Halloween Store in Porter Square, the busiest day of the year was--you guessed it--yesterday, with dozens of would-be vampires, werewolves, pirates and gorillas flowing in to find that last-minute costume.

The store, owned by Elise I. Freed, a freelance set designer and 1983 Wesleyan graduate, rents space just for the month of October. While it has attracted curious customers all month, "The past two days have been wild," Freed said yesterday. "Everyone seems to wait until the last minute."

This year's hottest items have been executioner and Ninja outfits. "Everyone asks for them. We've also sold zillions of blood capsules," Freed said as dozens of people milled about, examining such necessities as Groucho glasses, clown makeup, fake blood and skin-wigs.

The $40 Popeye and Olive Oyl masks carried the highest price tags, closely followed by the $36 female gorilla's chest.

A freelance set designer 11 months of the year, Freed originated the store's concept last October, renting a space near Harvard Square, when she was low on cash and out of work.

She bought her supplies from a New York gift warehouse whose catalogue she illustrated while in high school, when she first became interested in costume merchandise.

Business, while booming, is erratic. Many customers come in just to browse the collection of masks, from glow-in-the-dark skeletons to celebrity wrestlers to Richard Nixon. "You wouldn't believe how many people come in here, try on 97 different masks, and buy one $1.79 set of vampire teeth," Freed said.

Lucy E. Throckmorton, a store employee, said she was disappointed by people's lack of imagination.

Except one customer. "There was this one guy who wanted to go as a shower! We didn't have anything like that so I sent him to a hardware store," she said.

Freed plans an "everything must go" sale on Nov. 4 with 40 percent off. Although trick-or-treating will be over, Freed plans to be back next October