As the family has asked for donations instead of flowers, Hard to Find will donate 100 per cent of all profits made from the Olivia Newton-John tribute t-shirt to the Olivia Newton-John Foundation Fund, www.onjfoundationfund.org.
The foundation is committed to realising a world beyond cancer, funding research into plant-based medicine and other holistic and wellness therapies.
Breast Cancer UK head Thalie Martini told the BBC Olivia had left an "incredible legacy".
The charity was "particularly grateful for Oliva Newton-John's commitment to awareness raising of this devastating disease".
Speaking to CNN just after she had discovered the cancer had spread to the base of her spine, Olivia said she was "very lucky" to live where cannabis was legal.
"My dream is that in Australia soon it will be available to all the cancer patients and people going through cancer or any kind of disease that causes pain," she added.
Hard to Find is the site brings a curated community of product designers and artisans together with consumers looking for something unique, creating a more personal maker-to-customer shopping experience.
The Olivia T-shirt, $65, Hard to Find
The Olivia T-shirt is designed and digitally printed in Melbourne by Melbourne artist Jess McDonald. High Tees, is 100 per cent organic cotton (GOTS certified), printed to order and certified child labour free.
Shop the Olivia t-shirt here.