Defence Minister Jonathan Coleman has denied accusations the SAS is under-equipped for battle.
Last week an SAS soldier told a court martial at Papakura Military Camp he spent US$15,000 on his own kit while serving in Afghanistan.
"Being a young up-and-coming soldier and mad keen on gear and getting amongst it, I was on the internet daily buying stuff," he said.
"For myself and for my guys, it makes me safer in the combat environment."
The 29-year-old soldier, who cannot be named, was convicted of stealing military equipment and was found guilty of unlawful possession of "thunder flashes" - small explosives used to simulate battle noise - and had previously admitted disobeying orders by keeping a privately-owned gun in his barracks.
He was acquitted on charges of stealing a pistol holder and unlawful possession of live ammunition.
Judge Christopher Hodson, who presided over the court martial, fined the soldier $4700 but said he would not be dismissed from the Defence Force.
The soldier said he bought his own charging handles for his rifles because they were due for upgrade and the current handles were unsafe for ambidextrous shooters. He did not want to wait for official gear to be issued, he said.
The soldier also said he got some items, including JPoint weapon sights, from the US Army surplus bins in Afghanistan.
An Army storeman who worked with the soldier's squadron in Afghanistan, confirmed New Zealanders would help themselves to discarded equipment at the US Air Force base.
"Us Kiwis being kind of poor we used to go there and sign for stuff.
"There was a helicopter there at one stage that I saw that if you could fly it out and sign for it, it was yours. You could get anything you wanted there."
Labour defence spokesman Phil Goff told Radio New Zealand today it was incumbent for the Government to give soldiers the best and most necessary equipment needed to protect themselves.
"The fact that these soldiers had to go out and buy their own equipment suggests that the Government wasn't providing them what they actually needed."
However, Defence Minister Dr Jonathan Coleman said the SAS had the best equipment in the world. "We have given them everything they need to do the job."
SAS soldiers buying their own equipment had been a long-standing practice, he said.
"The guys are always going to go out and buy whatever's available online because they're top professional soldiers, they're real enthusiasts, but there's nothing wrong with the world-class gear they get [from the army], there's no question about it.
"It's a bit like sportsmen; they want very personalised gear. Now we can't give out 30 pairs of different boots across the defence force, but what we do issue is the very best."
A Defence Force spokeswoman said Judge Hodson's decision did not mean the soldier couldn't be stood down from the SAS, and that would be a decision for his unit to make.