Fast fashion is in its prime.

The May 8 grand opening of Primark — the Irish-born multinational retailer known for selling trendy clothing, home goods and beauty products at bargain bin prices — at 150 W. 34 St. brought Manhattan’s penny-pinched shoppers out in the masses.

Approximately 3,000 of them, in fact. As the affordability crisis continues to hit New Yorkers, they lined up from 3 a.m. to be among the first to experience the flagship, eager to get their favorite styles for a steal.

Quintasha Watson (a 34-year-old MTA bus driver) and Victoria Crowell (a 23-year-old recent college grad) are two sisters from Harlem who are already big Primark fans, previously driving to the American Dream location in New Jersey “maybe three times a month,” and love the store’s hard-to-beat prices.

“We’re finding bags for like $6, pants for $10 — we even got our niece a few outfits that were like $8,” said Crowell.

She also said that her family appreciates that they can put together full, fashionable outfits for a reasonable rate.

“(That) you can buy an outfit — get the top, bottom and put the whole outfit together for less than $20 — that’s awesome,” Watson added. “We’re all kind of in mid-recession right now … Living in New York City, rent is high, and even transportation is going up. People think that you have to spend $1,000 or more to look decent, when I’m looking at shirts right now, and I’m pretty sure they’re not past $10.”

“You can come in here, get a whole business outfit for an interview and look like you spent $500, but you probably spent $50,” she continued.

The new brick-and-mortar, which joins the ranks of similarly priced chains in NYC like H&M and Zara, features self-checkout and regular tills. It will be the store’s fourth NYC location directly within city limits — with others directly in Brooklyn, Queens and Staten Island — the 11th store in the state of New York and 40th in the US.

A-list celebs like Sarah Jessica Parker, Emily Ratajkowski and Andy Cohen were among the first to enjoy the new location at a pre-opening party for the brand on Wednesday night, where merchandise rings in at around $10 on average, according to a representative.

Other bargains include men’s tees, which begin at $5; boys’ sweatshirts start at $8; and women’s denim goes up from $12. Large luggage, the store’s most expensive item, can ring up at over $50.

Even the Empire State Building got in on the fashion-forward fun, lighting up in the brand’s signature aqua hue on Thursday in anticipation of the opening.

Friday morning’s dedicated linegoers were treated to various forms of entertainment and goodies, like beats from DJ Luna Rósa and sweet treats from Joe’s Coffee. 

Beatrize Villanova, a 31-year-old from Brazil who was visiting the Big Apple on vacation, told The Post that she’s been to Primark stores twice while visiting Europe and wanted to take a peak at trending budget-friendly styles to bring home.

“I think it’s very fresh,” Villanova told The Post. “Everything that’s trending right now, they have here.”

“Herald Square is the center of fashion in the U.S. and global,” Kevin Tulip, president of Primark US, who’s been with the company for 25 years since he was 16-years-old, added to The Post. “So being able to open a 54,000 square foot flagship store in the center of the fashion capital of the world is something that we’re incredibly excited about.”

Naquan Peterson, a 29-year-old security worker from Brooklyn who came across Primark’s grand opening by accident but decided to stop in to buy blue and pink outfits for his coming baby’s gender reveal (and picked up some Knicks gear along the way), emphasized that his Primark haul  — which he estimated to be around $60 — probably wouldn’t be possible at other retailers for the same price.

“Life is hard for everybody,” Peterson said. “We’ve got to make it work with clothes, with food, gas is going up. So I feel like we’ve always got to just think smart … Imagine me going to Macy’s. I’d probably get like two things — I couldn’t get all of this. Macy’s would probably be, like, $200.”