Over a few weeks, donors had pledged just under $40,000 if the total was met by an April 17 deadline.
"When I opened Moustache, a lot of people told me it was a silly idea but I went for it anyway," she said.
"The bus is also an act of doing something out of left field and pursuing a dream that isn't so conventional.
"We have so many fans coming from outside Auckland to visit the shop I thought, 'Why not build a big bus and take Moustache to customers who can't get to us'?"
The Pledge Me page says the shop will close "due to unexpected events outside our control".
In September, Yang said the shop's future in central Auckland was at risk because of soaring rents.
It sparked an online campaign to save Moustache, with chart-topper Lorde posting on Instagram: "Aucklanders — if you've been to moustache (the awesome milkshake/cookie place by the civic) you'll know how hard these people work and how much it would suck if they had to close. Sign this petition and hope for the best (this is partly a selfish post because i go there for peanut butter+nutella milkshakes EVERY WEEK."
Click here for the Pledge Me page and support Moustache.