Seller trying to renegotiate price after buy now used

Legally, if that was a genuine mistake, yes they can do that under the contractual mistakes act. Of course "genuine mistake" is the important words and then the hard bit is to prove in is genuine or not. it would however be looked at in pretty bad tate though.

The sale is only binding in regard to the price you purchased it for on the buy now. The seller should not inflate costs after close of auction and is not part of the code of conduct or Terms in Trade me policies on selling. Also refers to Consumer Guarantee and Fair Trading Act. This has been on the message board before. But if they are not going to go ahead you can't make them.

If they are going to back out you can give them the appropriate feedback stating what has happened so other buyers can be alerted to this behaviour. Maybe consider reporting the seller to Trade Me in the Trust and Safety part of Help. Or Contact Us, Live Chat and then ask for a real person to report it to.. 

Absolutley, as L says. However reporting them to TM maybe a waste of time as if it was a genuine mistake, by not completing trade at the original price, they are following the law of the contractual mistakes act, and TM authority is not above the law. But it maybe good for TM records if this was an on going recurring situation

Seller being casual or In Trade and their type of feedback might help in deciding Scott.

3 weeks ago there was a similar situation for another buyer on the message board called Seller wants to increase price after auction close. Scott, you might like to check it out as trade me stepped in and helped out there. 

Sounds very much like an honest mistake as the seller has said, in which case you can't hold them to it. If you don't want at the new price the seller has suggested, let them know and continue your search.