Ms Sunnex said it was hard to keep track of items that went through the shed, as new stuff was taken in every day and old stuff was also taken quickly.
Mrs Manuka said "some crazy things" often arrived - someone once brought in a $300 Calvin Klein skirt.
Both women said the shed would not work if it wasn't for the support of the community.
"There's no money involved," Ms Sunnex said.
"People can come in and walk out with rubbish bags full of stuff."
Mrs Manuka mentioned one occasion when three girls in a hatchback arrived, and by the time they left Mrs Manuka and Ms Sunnex were still squeezing items through the car's back window.
She said the system "just works, and it works everywhere".
People could come by any time to pick things up or drop off items, and if the shed door was closed they were welcome to open it and rummage around inside, they said.
Mrs Manuka said she was "a little bit humbled" by the Pride of NZ Award nomination, but thought Ms Sunnex also deserved one as they started and ran the Koha Shed together.
Ms Sunnex said she didn't mind. "I'm going to have enough people to carry my coffin and that's probably the best thing in life," she said.
Mrs Manuka said, "Me and Sherron are really proud of what happened and how far we've come."
The nominator said Mrs Manuka made her "proud to be a Kiwi".
"I met her one day about a year ago when I was down and out and had been disowned [by] my family, homeless as a pregnant 16-year-old," the nominator said.
"I had nowhere to turn. She heard my story and really cared about me. She helped me to find accommodation, furnished my house, gave me a carseat, high chair, clothes for baby and myself, and even put artwork in my house when I moved in."
Mrs Manuka and Ms Sunnex are also hoping to set up an emergency food bank.
The Koha Shed can be found on Facebook.