Parents are clamouring for a doll that helps send little ones off to sleep by "sounding a bit like Darth Vader".
The Lulla doll, developed by Icelandic mum and psychologist Eyrún Eggertsdóttir, plays a heartbeat and breathing sounds that replicate the sound a sleeping baby would hear.
According to the doll's Indigogo page, where its creators first raised funds to start manufacturing the product, "Lulla's unique patent pending design was inspired by research on kangaroo care, the effects of heartbeat and breathing sounds, and the effects that smell, sight and touch have on babies and small children.
"When the chest is pressed, Lulla plays a real-life recording of the breathing and heartbeat of a mother at rest. Her name is Gudrun, she is a dear friend, a mother of four and a Kundalini yoga teacher."
The sounds of a mum at rest are what makes the doll different from other white noise machines and apps, according to its creators: "Lulla's aim is to help babies stabilize their own breathing and heartbeat, resulting in longer and better quality sleep as well as added security."
Now that the doll is available for sale around the world, parents can't get enough of it.
Reviews on the Indigogo site and the company's Facebook page rave about the doll and its ability to get little ones to sleep - and that's all helping push prices up.
The Lulla doll usually sells for $99, but a recent bidding war apparently saw prices reach a whopping $350 on eBay.
Michelle Green, Australian distributor, said she's been overwhelmed by orders.
"It's crazy," she told the Daily Telegraph. "I'm packing and they're going out the door as fast as I can get them."
"It does sound like Darth Vader but, as I tell mums, most toddlers and babies haven't seen Star Wars."
While the dolls have sold out on Amazon and other third party sites, there's some good news for parents desperate to get their hands on one: they're now available for pre-order on the Lulla Facebook page, with delivery due in August.