The Hope4Cancer Institute in Tijuana provides an alternative treatment called Salicinium therapy, which the clinic says can kill cancer cells by disrupting a key enzyme.
Now the family are trying to raise $60,000 to travel to the clinic in December.
The parents already have $10,000 - a deposit they were going to use to buy a house - and friends have started a Facebook page which has raised $2000 in one week.
Mrs Gailey said although there were no guarantees, she and her husband wantedto give their daughter the best chance ofsurvival.
"We wouldn't be able to forgive ourselves if we didn't try."
The pair will take Tayler and their three other children, Carter, 7, Hunter, 5, and Archer, 1, on the three-week trip because "realistically, we don't know if we'll get another family holiday again".
Two weeks after her second birthday, Tayler underwent seven weeks of radiation treatment.
She lost some hair, but Mrs Gailey said her youngest daughter was "a trouper" who wasn't sick and coped as well as she could with the treatment at Starship hospital in Auckland.
Mrs Gailey, 25, noticed something wrong with Tayler weeks before her first birthday.
"I knew for a long time. She struggled to do things that shouldn't have been a struggle. She would always drag one leg when she crawled."
Mr and Mrs Gailey pestered doctors, including specialists, for answers and discussed Taylor's developmental milestone delays with Plunket.
She was referred to the Child Development Centre in Hamilton but it wasn't until Tayler began squinting at 13 months and her eye turned inward that doctors started to suspect something more serious.
An MRI scan led to the diagnosis and to radiation therapy.
