In Parliament to day, opportunistic hologram David Seymour attacked the government's proposed gun buyback scheme, claiming that it would be costly and unsuccessful. Its success is obviously up to gun owners and police - and I would hope that they take a hard line on criminals hoarding prohibited weapons. But as for cost, the buyback would be cheap at twice the price.
Just do the maths. There are 300,000 gun owners in New Zealand. Not all of them will own illegal semi-automatic weapons, but a large proportion will. After today, those who do not turn over their weapons will be criminals, subject to five years imprisonment. That's a high enough penalty to require a jury trial, which costs over $1,000 a day in jury costs alone. A judge costs another $1,000 a day, the prosecutor twice that, plus there are court staff. So, the cost of simply bringing these people to trial is ~$5,000 a head. Prosecuting all of them would cost ~$1.5 billion, and that's without even getting into the astronomical cost of punishment ($300 / day, plus building thirty times as many prison cells as we have at present).
Or, we can just buy their now-illegal guns. Its cheaper. Its unquestionably easier. Its more humane than throwing people in jail. And it would let police focus their resources on the gun owners who refuse to turn over or account for their weapons, meaning much better enforcement. But I guess ACT isn't interested in any of those things.