Children's entertainers Chloe Manford, left, and Amy Manford host a Frozen themed party for Beth Cairns (4), Daisy Martin (4) and Evie Martin (3). The Disney film Frozen is the highest grossing animated film of all time. Picture: Megan Powell/The West Australian

In lounge rooms across WA this weekend, little princesses will be conjuring snow and repeatedly singing, "Let it go, let it go".

Disney movie Frozen has become such a phenomenon that there are few households with young children that have not been swept up in the fairytale of Princess Anna and her sister, Snow Queen Elsa.

It is the highest grossing animated film of all time - recently surpassing Toy Story 3 with $1.1 billion - and the film's surprise success has spawned unprecedented demand for merchandise.

As Disney scrambles to replenish sold-out stock, parents are swamping sites such as eBay where Frozen toys and outfits are selling at inflated prices. Dresses that retailed for $30 to $50 now sell for several hundred dollars.

WA party planners are capitalising on the frenzy after being inundated with requests for Frozen-themed children's parties.

Natasha Vine from Encore Kids Parties is arranging more than 15 Frozen-inspired parties in Perth every weekend.

"I can't keep up with demand. Every day the phone is ringing for Frozen," she said.

She and co-owner Di Rankin employ real-life sisters, soprano singers and WA Academy of Performing Arts students Amy and Chloe Manford, to perform as Anna and Elsa, charging $370 for up to 15 children.

"I get three-year-olds who know all the words to every song, it's crazy," Amy said.

Tammy Lawson from Mystique Cake Creations charges $220 to $550 for a Frozen birthday cake, and is making at least one a week.

The film has infiltrated the homes of Carolyn Cairns and Jean Perkins, whose daughters Beth Cairns and Daisy Martin are "constantly" singing the songs from the Oscar-winning soundtrack.

"It's the first thing Beth sings when she wakes up and the last thing she sings before she goes to sleep," Mrs Cairns said.

Ms Perkins bought her daughter a Frozen dress on eBay as a reward for good behaviour but after accidentally buying two she went to sell the second one and discovered prices for the dress had tripled to more than $90.

Eagles captain Darren Glass and wife Alicia hosted a Frozen birthday party for their daughter Zara's third birthday last month.

"She and her sister Mila watch it together and they love the music and the costumes, it's taken over their lives," Mrs Glass said.

Blogger Rayne Embley, who attended the party with daughter Autumn, said the movie's storyline was partly what made it so popular.

"It's not so much about finding a husband and getting married, it's about family and sisters looking after each other," she said.