"This is a unique opportunity to acquire a piece of New Zealand history," the seller wrote.
"This is a rare chance for you to snatch up a piece of immaculate memorabilia.
"And finally you will find the Pak'nSave logo with barcode in the final picture to verify the authenticity of the item.I hope this brings as much happiness to your family as it did mine."
Prospective buyers of the item were, however, intent on rigorously testing the plastic bag's authenticity.
One TradeMe user enquired "Would I be breaking the sale conditions if I use it again?"
The Nelson seller was cautious in reply:
"Although I wouldn't recommend it, I have been proven wrong on multiple occasions that the bag can withstand more than a one time use. Please feel free to do so at your own risk."
Another potential buyer was nervous about safe delivery of the bag.
However, the seller assured it would be packed in "not just bubble wrap, every precaution will be taken to ensure safe delivery of the antique".
Another user was simply amazed at the bargain they were in line for, asking "Why is this so cheap? It's easily worth $500 at least."
The gracious seller insisted, "I just wanted to give everyone an equal opportunity to obtain such a rare collectors item."
Instead of the single-use yellow plastic bags, Pak'nSave supermarkets are now offering shoppers paper bags at a cost of 20 cents or reusable plastic bags at a cost of 25 cents.