Price, a mum herself, asked people not to judge the family's situation, as sometimes "people can't cope with certain stuff and it doesn't matter in the grand scheme of things".
The dress in question was a distressed grey tank dress, in a jersey fabric, featuring a rainbow heart print, by UK brand Next.
Her issue was that this dress came from a line released about three years ago, which meant finding a replica for Elsie would be a challenge.
Price offered to purchase the dress from anyone willing to part with theirs, for the happiness of her friend's daughter.
Within a few hours, the response to the posts were extraordinary, as thousands of people around the world jumped to help Elsie and her family.
Some tracked down copies of the lost dress on eBay, others offered to part with their own children's dresses and some even said they were able to sew an exact copy for Ms Bell's daughter.
One woman's 12-year-old daughter, Mila, saw the post and offered her own dress to Elsie.
Price explained that Mila had told her mum "she would send it to us".
"I told the mum to tell Mila how kind she is, she's given my friend some breathing space and made her daughter's day too," Price wrote.
"It totally restores your faith in human nature. Absolutely bowled over by the kindness of strangers."
Price said Elsie might "eventually grow out of her fascination with this dress", but finding a replacement was her mother's immediate concern.
"It would just give her and her mum a bit of breathing space and make the dress stress less," she wrote.
Many people wrote in, explaining they had been through similar situations themselves or with their children.
The message spread so far that the Next corporate office even contacted Ms Price, saying they would check with their suppliers to "see if we can produce a few more batches of this dress".
Elsie's mum, Bell, sent a photo of her little girl back in her favourite dress, which Price posted to Twitter to thank everyone for their help.
"You're amazing and your mum's are pretty amazing too for raising such lovely daughters," she wrote.
"But mostly you're great because you've made a little girl really happy to continue to be in her favourite dress."
