A canny plumber from Nelson has sold a single-use Pak'nSave plastic bag on Trade Me for $52.
The auction closed on Tuesday night and received 47 bids.
Seller Nairn Wilson, 18, told Stuff he was "definitely surprised and pretty excited" by the response his auction got - and that he'd rushed out to buy a gold frame from K-Mart for the bag, along with bubble wrap to post it in.
Trade Me's Millie Silvester told Newshub the sale was "topical and they're having a bit of fun with something that all of New Zealand is talking about".
It's not the first time plastic bags have been listed. Last year someone sold 200 single-use bags ahead of the ban, calling it a "Bag-ageddon - Emergency Survival Kit".
Most shoppers Newshub spoke to welcomed the bag ban.
"It's great, we really support it. We have our own bags - not today though!" shopper Carolyn Roberts-Thompson said.
Another said it's going well, with people quite happy to follow the rules.
But shopper Anne Spencer pointed out, "There's a lot of plastic around meat, around vegetables, and I think they should have done that first."