Membership at Townhouse will cost $2,400, according to Trustman. After paying, a customer’s dining and drinking bills will be deducted from that total. Stavrianopoulos, who’s opening the Friday Club with his partners, promoters 6one7 Productions, along with the Ivy Restaurant Group, said he, too, envisions a slightly more mature audience, one that wants a place to socialize that’s less frantic than a public bar.

“A big inspiration for this comes from my own lifestyle,’’ Trustman said last week. “After dinner, I often want to have a liquored up cappuccino or a fabulous glass of port and hang out with my friends. I don’t want to sit at the dinner table anymore, and, at 53, I certainly don’t want to go to a club. I need somewhere in between.’’

And yet, he and other club owners are betting they will. The Foundation Room, the private club-within-a-club at the House of Blues, has nearly 600 members who’ve paid between $1,000 and $34,000 for various levels of membership to linger in the luxurious dining room and get access to sold-out shows, according to Foundation Room sales manager Robert Dougherty. In September, Kathy Trustman, owner of the Metropolitan Club restaurants, will open a private club called Townhouse inside her new restaurant, Met Back Bay, on Newbury Street.

But is it really? It’s tough to believe that with the economy still uncertain and jobs scarce that local clubgoers and VIPs are willing to shell out serious cash for the separate entrance and private key that Stavrianopoulos promises.

The Friday Club, slated to open in September after many delays, is part of a mini-boom of private or semi-private clubs sprouting up in the city, including the Foundation Room on Lansdowne Street and the soon-to-open Townhouse in Back Bay. Other clubs are experimenting with insider nights that have the feel of private clubs. “The demand is definitely there,’’ Stavrianopoulos said as he gave a tour of the basement space.

The door that once welcomed visitors to a museum devoted to the life of Christian Science Church founder Mary Baker Eddy will now greet a very different type of guest. The wooden behemoth — purchased at auction — has a new address at the Friday Club, a private, members-only club in the basement of Stoddard’s Fine Food & Ale in Downtown Crossing. To get in, entrants will be required to pay a membership fee (or be a close friend of someone who has paid), Stavrianopoulos said. They’ll also have to be recommended by another member.

This is the door where members will be required to use their key to enter,’’ says nightlife promoter and club owner Frankie Stavrianopoulos, gesturing to a hulking seven-foot-plus door that was transported from the Longyear Museum in Chestnut Hill. “But there will be someone on the other side to make sure that they’re a member.’’

“We’re looking for the 25-to-55 demographic,’’ he said. “We’ll get people who want to be out without a hassle. They want to see the bartender chip away at the ice and make an original cocktail. We’re not going to be serving vodka Red Bulls or flavored vodkas.’’

Carefully mixed craft cocktails are the cornerstone to many of these clubs, according to international bar consultant Angus Winchester.

“I see a growth in members clubs around the world because the cocktail is rediscovering its place as a culinary delicacy rather than just a way of getting pie-eyed,’’ he said. “When you use fresh ingredients, bars need more time to make them and to restrict the number of people ordering them — hence the need to make bars members-only.’’

That said, many local bars have been making craft cocktails for years, and private clubs are not new to Boston. The private, after-hours club Rise has been in operation for more than 10 years, but it is focused on dancing, DJs, and electronic music.

Then, of course, there are the staid, classic clubs, where the city’s wealthy elite have broken bread and enjoyed their cocktails for more than a century, said Boston College historian Thomas O’Connor. The Algonquin, the Union Club, the Tavern Club, and others remain active, and, as Governor Deval Patrick discovered when he canceled a speech at the private Clover Club last year, they can still set up their own rules, such as men only.

“At the time these clubs were at their most popular, there was no radio, no television, and no movies,’’ O’Connor said. “Here they were facing a long night with nothing to do, so they’d go to their club. There was always a conversation happening.’’

While the old Brahmin clubs can feel like relics from another era, the new members-only nightclubs toy with a few of their trappings. The Friday Club first described itself as a “gentleman’s club,’’ for example, which led to confusion about just who could join, but Stavrianopoulos says the description has to do with the clubby décor. He makes clear that members of both sexes will be allowed to join. As for the cost of membership, Stavrianopoulos is coy, saying it will be “more than a dollar, less the $6,000.’’

At Prohibited, a speakeasy style club in the Back Bay, more than 1,500 people have signed up to learn the password each day to gain admittance to the basement den near Symphony Hall. Membership is free, but it comes with its own set of rules. Cellphone calls are forbidden, as are baseball caps. “Brazen come-ons’’ are also a no-no; men are encouraged to send a drink to a woman they have their eye on. If she’s interested, she’ll let the bartender know.

“We do enforce the rules,’’ says manager Ashley Forsyth. “But we do it playfully. We want people to have a good time.’’

The new club owners believe their locations will be havens that will allow executives, celebs, and athletes a place to unwind without being hounded by gawkers and autograph seekers.

“My daughter worked on the film ‘Shutter Island,’ and all the stars who worked on [it] were looking for a place like this to go,’’ Trustman said of Townhouse. “And that inspired a lot of the idea for me.’’

The membership-only trend is, in many ways, simply an outgrowth of the speakeasy trend that’s been popular for years, and continues to lure crowds. On Sunday nights, Trina’s Starlite Lounge in Somerville draws the blinds and hosts a rotating cast of well-known bartenders for a hush-hush (patrons enter through the backdoor) party of impromptu cocktails. The night is often standing-room only.

But the question remains: In a still-soft economy, will these membership-based businesses draw enough interested customers to make a splash?

“I see [private clubs] as an extension of the whole luxury box mentality,’’ says Lauren Clark, who writes the blog DrinkBoston (www.drinkboston.com). “I think they’ll do fine. We’re in a recession, but there are plenty of people who are still making money who want that kind of experience. I may not go there, but I know people who will.’’

Christopher Muther can be reached at muther@globe.com.

© Copyright 2010 Globe Newspaper Company.