Costco and Sam's Club shoppers are rushing to buy knockoff versions of a pricey Anthropologie mirror that has gone viral online. 

The floor-length Anthropologie item, called the "Luisa Mirror," is available on the multibrand retailer's website for nearly $1,200. 

"Delicate hummingbirds and gilded flowers adorn the trim" of the resin and iron framed mirror, which measures 72.5 inches high by 34.7 inches wide, according to Anthropologie's website. 

Discount shopping clubs Costco and Sam's Club are capitalizing on consumer demand for the detailed design by selling their own, much cheaper versions.

The replicas appear to be so popular that Costco's imitation, called the "Ravena Floor Mirror," is no longer available on the retailer's website, according to Costco fans who track the retail club's stock and post about it on social media.

Laura Lamb, who tracks her favorite store's new arrivals and products on her Costco Hot Finds Instagram account, said she was delighted when she saw the Ravena mirror in stock at a Costco store she visited. 

"Finally!!! The Costco mirror is making its rounds through the regions and it was worth the wait!!!" she said in a video she posted. More than 130,000 Instagram who viewed it tapped the "like" button. 

In her video, Lamb showed about eight mirrors in stock on display at the Costco store. A search for the mirror by item number on Costco's website, however, yielded zero results. 

Costco did not immediately respond to CBS MoneyWatch's inquiry into the hot item's availability. 

At $150, the Sam's Club knockoff, called the Azalea Park Filigree Floor Mirror, and named after a neighborhood in Orlando, Florida, also retails for a fraction of the weightier Anthropologie mirror.  To be sure, it's not a perfect copy, and is less ornate than the original version. For one, its frame does not feature hummingbirds. 

The Azalea Part mirror is also listed as out of stock on both the retailer's website and in stores. Sam's Club did not immediately respond to CBS MoneyWatch's request for comment on the item's availability. 

It's common for discount retailers to produce cheaper imitations of pricey designs that strike a chord with consumers, making top-selling items affordable for the masses. 

"The most successful enterprises and founders are often those who didn't invent the product, but who instead iterated and scaled to successfully build a mass market for that product," University of Washington Professor Margaret O'Mara, said in an article by Inc. on copycats latching onto viral trends.

Shoppers must be members to purchase goods from Sam's Club and Costco warehouses. 

Costco recently clamped down on shoppers attempts to evade the membership requirement by using others' cards. 

Instead of just waving the membership cards at a staffer, shoppers at select Costco locations around the U.S. are required to digitally scan their cards, to ensure nonmembers aren't taking advantage of perks reserved for members.

Megan Cerullo

Megan Cerullo is a New York-based reporter for CBS MoneyWatch covering small business, workplace, health care, consumer spending and personal finance topics. She regularly appears on CBS News Streaming to discuss her reporting.