In 1971, Montreal became a city with a used record shop. Four decades and countless copies of Dark Side of the Moon later, they’re still slinging vinyl at the store that started it all. Cheap Thrills, humble and mighty, sanctuary of books and music in the heart of downtown, celebrates its ruby anniversary on November 9. And the party’s going to be a good one.

"It’s historic!" declares Caila Thompson-Hannant, who makes smouldering gold pop under the name Mozart’s Sister. She performs at Wednesday’s birthday bash along with Pigeon Phat and Alden Penner’s folk-gospel project Hidden Words. "It’s amazing for any store to be open 40 years. For a record store, it’s crazy."

"I wish I could say there was some kind of secret trick," replies Guy Lavoie, Cheap Thrills’ manager. When I reach him, he’s at the shop. Of course he is – he’s there every day, 11 to 6. And he has been there, more or less, since 1981, four years before Thompson-Hannant was born.

Cheap Thrills claims to have been Montreal’s first used record store. Inspired by a trip to California, Janet Dawidowicz opened the original shop in 1971 with money from a car insurance claim. In the beginning, Lavoie recalls, "it was just Janet in an empty apartment, buying records off people. I thought it was such an incredible idea. Anyone who couldn’t afford new records, like me, suddenly you could get two or three a week."

For a long time, business boomed. The store expanded in the early 80s, growing from that apartment on Bishop Street to their second (and current) location on Metcalfe. Stock grew to include books, tickets and new music. Catherine Deneuve stopped by to pick up a collection of Peanuts comics. And even after they closed their first location, in 2000, cozy Cheap Thrills kept on chugging, a landmark for the Montreal scene.

Lavoie, 61, says he remembers the heyday of Harmonium and Beau Dommage, the era when "everyone hated disco," the years "when nobody wanted records by Amon Düül or Fleetwood Mac." He remembers the Italian restaurants that used to be downstairs (there have been three of them), and the dawn and dusk of cassettes. "We’ve changed as we’ve had to change," he explains. "We haven’t been greedy. We pay fair, we sell fair."

The shop has also been a friend to local musicians. "Just about anyone can walk in with their record and we’ll try them out." They have long-time links with labels like Constellation, and Alien8, co-founded by Cheap Thrills staffer Gary Worsley. "We had Arcade Fire stuff when they were doing it themselves, without a label, just bringing it around."

Cheap Thrills’ upcoming birthday party is a testament to their cred. In a city of next big things, Mozart’s Sister is one of the nextest – a one-woman dance floor ravisher, channelling Arthur Russell, Prince and a little Lou Reed. Thompson-Hannant says she set out to make "stripped-down dance music, without a whole lot of lush shit." But there’s whistling too, a debutante’s coo and the stubborn bass lines that Thompson-Hannant brought as a member of Think About Life.

"I want audiences to feel that they’re seeing something genuine," she says. "Not that I’m posing or have some kind of hardened front." Vulnerability, she argues, is an engine for swoon and swagger. "Being on stage is a chance to be free. It’s an opportunity to really ride the moment and be candid and positive, to try and include everyone."

So far, Mozart’s Sister has only released three songs, but she has plans for a debut album. And if Lavoie has his way, Cheap Thrills will be around to sell it. "We’ll still be here in 10 years," he says, "I’m pretty sure." At the end of the day, the store isn’t just one of Montreal’s treasures – it’s a treasure that need never go away.

"You try to get stuff that’s interesting," Lavoie murmurs, like he’s disclosing a magic formula, "and you sell it to people."

Cheap Thrills 40th Anniversary Party
w/ Mozart’s Sister, Hidden Words, Pigeon Phat
At Casa del Popolo
November 9
www.cheapthrills.ca