A Father's Day promotion at an Auckland gun shop offering a "mystery firearm" for $1 to the first person to spot it on the racks has been labelled sick, sad and irresponsible.

But the man behind the bargain stands by his offer and says the dad who gets the gun will be "God blessed".

As part of its annual Father's Day sale Gun City in Mt Roskill is offering a special deal to one lucky punter on Saturday. If they spot the gun with the $1 price tag - it's theirs to buy, providing they have a current Firearms Licence.

But anti-gun lobbyists say the promotion may send the wrong message to the public.

Professor Kevin Clements, director of the National Centre for Peace and Conflict Studies at Otago University, said there were already "more than enough guns" in New Zealand.

"I think that it is a very sick and sad promotion for Father's Day," he said.

"New Zealand already has 230,000 licensed firearms owners and over a million weapons. The assumption that a father needs or wants a new gun for Father's Day sends all the wrong messages to children and partners.

He said advertising a gun for $1 would attract a wide variety of bargain hunters - and most would already own guns.

"This $1 gun will be surplus to their requirements. It is not a responsible promotion. It is an inducement for gun lovers and bargain hunters to come into a gun shop.

"It is dangerous because the advert suggests that purchasing a gun is not very different from a fairground lucky dip when, because of its potential lethality, it should be a very serious, deliberate decision subject to specific rules and regulations."

Green MP Keith Locke said the promotion was "disturbing".

"I think it's completely the wrong attitude towards guns and the sale of guns," he said.

"Surely the whole context of the sale of guns should be that guns are sold only for particular legitimate purposes. Hunters, for example, buy a certain type of gun for hunting."

But Gun City owner David Tipple stood by the sale and said it was a "genuine gift" from one gun lover to another.

"What does it matter if a guy pays a dollar or $10,000 for the gun? What difference does it make?" he said.

"Picture this - some kid who can't afford to buy his father a gun. But say he's 18 or 20 and has his Firearms Licence, he can give that gift to his father.

"This is a genuine gift from us, and God bless the guy who gets it."

Mr Tipple said the only problem with the promotion was a backlash from those who did not understand and feared guns.

"These people are dealing with that kind of ignorance and I feel really sorry for them. What else are they afraid of?

"The reality is we live in a country where firearms cause less harm than fly spray and they have nothing to fear.

"It's tragic that the vocal minority are normally speaking from ignorance. Just because the firearm is sold cheap doesn't mean it poses a threat to society.

"The person who owns it has been vetted and they're entitled to own a firearm, so what difference does it make if their economic circumstances wouldn't normally allow them to - but as a result of us subsidising it - they can."

Mr Tipple was reluctant to reveal any details about the gun, but said it was "a particularly good deal" and worth between $500 and $1500.

"It's a lot of money, it's a big reduction. But that's what we're prepared to do as a gift for Father's Day."

He said the person who found the gun must be the buyer - eliminating the possibly of unlicensed people flooding to the store to try to spot the bargain.

"The buyer has to find it, has to identify it ... once he's identified it and once he's proven that he has a firearms licence, he can buy it."

Mr Locke said the promotion was the wrong approach to gun sales.

"We're not trying to cultivate glorification of guns in our society in the younger generation ... it's the sort of thing you'd expect more in America than in New Zealand. It's not the sort of thing we want to see here."

Mr Clements said encouraging people to buy more guns was wrong.

"I think that the existence of 1.1 million guns is already far too many for a country of 4.4 million people."

He said promoting "gun cultures" was also dangerous.

"Gun cultures survive by promoting what is known as 'hyper masculinity'. Such hyper masculinity is somewhat out of sync with a masculinity that favours good parenting, family attachments, equality, sensitivity to women and so on.

"The messages that Gun City are sending are likely to heighten gender divisions and create something of a pall over what should be a day when fathers immerse themselves in family, friends and the joys of home."

A police spokesman said he did not believe the promotion breached the Arms Act.

"But obviously the seller must comply with the act in terms of the sale and the purchaser must hold the appropriate firearms licence."