Is it against policy?

It's a Buy Now and Auction listing, and I opted for the Buy Now option. The seller specified the pickup time but didn't mention the need for upfront payment in the Description. They only communicated this requirement via email. I requested the seller to list another item for the upfront payment. As a result, we had a dispute, and the seller suggested calling off the trade, stating, "Let's call the trade off, mate. I don't have time. You should be very careful before you bid. Ask questions before you bid. I will have to flag you as well on Trade Me, and I have friends working for Trade Me. T...