The British parents of two breast-fed, unvaccinated, "free-range" children are seeking crowdfunding help to pay for a farmhouse in Costa Rica, where they hope to live a "self-sufficient" lifestyle.

Adele and Matt Allen are asking for the equivalent of $173,000 on the website FundMyTravel so they can live outside "the system" with their children, five-year-old Ulysses and one-year-old Ostara. The Allens want to use the money to buy land in Costa Rica so they can "self-build" a home in close proximity to wildlife and nature.

"Our ultimate goal is to become self-sufficient," the couple wrote on their crowdfunding page. They say they've been inspired by other off-the-grid families to "create a business, home and lifestyle which can show people that they don't have to comply to the constraints of 'the system.'"

The Allens' children still drink their mother’s breastmilk, because the couple believes the weaning process should be a "mutual decision" between mother and child.

"It's something that's just as natural as a hug," Adele Allen told Barcroft TV, in a video posted to the Allens' crowdfunding page.

The Allens say they'll eventually homeschool their youngsters, although they don't believe in "pushing traditional learning on the kids at a young age."

The self-described "unconventional parents" shun just about any method promoted by traditional medicine, too. They don't believe in vaccines, they treat a common cold with lemon water, and they treat an eye infection with a few drops of Adele's breastmilk. Adele says both children were born using the lotus birth method, which involves allowing the umbilical cord to dry up and fall away naturally, several days after the baby has been born.

Adele Allen says she takes the same approach to health with her children as she does with herself. "If I had something serious like cancer or such, I would definitely take the natural path," she told Barcroft TV.

The Allens also don't like to put shoes on their children's feet, despite facing criticism from strangers when the kids are seen in public. "It's the greatest way for her to feel alive," Matt Allen said of his daughter, Ostara.

While they preach an all-natural lifestyle, the Allens currently live in a one-bedroom flat in Brighton, England, where they all sleep in the same room.

The Allens have been facing intense criticism since their crowdfunding campaign launched on July 19. During an appearance on the U.K. television show "This Morning" last week, one-year-old Ostara urinated on the set during a live interview, while her brother Ulysses jumped around on the couch. The incident touched off a flurry of outrage on Twitter, under the hashtag #offgridparenting.

The Allens have also been taking a lot of flak on their crowdfunding page.

"How about paying for your freaking vacation yourself, like the rest of us do, and work for it," Marlene Blanshay wrote in the comments section.

"Earn the money from the sweat of your brow," Robert Padilla added. "Self-indulgent and self-entitled is what I see."

"So to live with nature and be 'self-sufficient,' you need strangers to give you £100k?" wrote Carlos Sousa. "Just what part of being 'self-sufficient' don't you understand? You're raising your kids like they live in the jungle anyway."

The family announced in a Facebook post on Monday that they recently passed a review with social services.

The Allens had raised the equivalent of $250 from 13 donors by Wednesday morning.

They say anyone who donates to their campaign will receive a digital copy of their upcoming self-published book, "The Unconventional Parent."