Used 'buy now' feature - but on contact for payment seller is wanting more money

I purchased an item using 'Buy Now', after receiving the 'congratulations' email from trade me I emailed the seller to organize payment. The seller 'thanked' me for my interest in the item and stated that they were new to trade me and had put the item on for the incorrect price and asked me to pay $260 rather than the $180 I won the bid for, if I was happy with this the sale would 'proceed'. The seller has 5 other items listed for sale on trade me ranging from $100 to $350 all with 'buy now' prices, so I am not convinced that they made a mistake. None of the other items have had price adjustments, which I would have expected if the seller was truly confused. After I responded to the email stating that this was an unusual request and that I would prefer to go ahead with the $180 vs the $260 the seller has not contacted me again and has re-listed the item on Facebook market place. I have the ability to leave negative feedback for this seller - I am not sure if they realize this? I am just wondering what I can do before I go ahead and place negative feedback and possibly report the listing to trade me. Thanks.