Rebel Sport boss Rod Duke said their Team New Zealand stock was "goneburger".
"There might the odd bits and pieces at some of the stores but for the most part it's just gone, all sold out."
Duke said he found the racing "terribly exciting".
"People might've thought it'd go on a bit longer than it has - obviously our buyers thought that too."
Sales of the lucky red socks made famous by the late Sir Peter Blake have also skyrocketed.
A Sir Peter Blake Trust spokeswoman said they had sold 13,000 pairs of red socks; the bulk of those sales coming this month as America's Cup fever has gripped the nation.
"Hopefully we've got enough stock to keep up with the demand," she said.
"We've had Facebook messages from New Zealand and Australia and around the world asking about where they can get red socks.
"There's a real frenzy at the moment. We love how the country gets in behind it every time."
The socks can be picked up at redsocks.co.nz for $6.95.
The upsurge in red socks sales comes just before Red Socks Day, which falls on July 7 this year.
Red socks have almost completely sold out at The Warehouse. At its Newmarket store staff member Ata Marsh said demand for red socks has "been so crazy".
"We've only got three pairs left, of children's socks.
"Once [Team New Zealand] started winning people just started coming in and taking the socks, they've been buying not one or two but six or seven pairs," she said.
Maritime Museum front-of-house supervisor Ryan Anderson said they've sold 200 pairs of red socks in two weeks.
"We have completely run out of them," he said.
