buyer does not want to pay via PING and asks for my account details

You may find that you lose the sale as some buyers are reluctant to use Ping. 

There's nothing out of the ordinary about accepting an online payment.

I recently encountered a similar issue with an overseas buyer not wanting to pay via Ping due to extensive bank fees at their end. I didn’t want to incur bank fees either so I offered to cancel the trade if they didn’t want to pay using Ping. I knew they really wanted the vase as they were a collector…they paid by Ping ;)

Absolutley nothing wrong with a buyer doing a bank deposit. It will also save you ping fees on the transaction. While TM do not put bank deposit in their payment options, it is of course still a very valid option than many buyers prefer. At the end of the day as the seller has specified ping in the listing, the seller can demand that, or cancel the trade, but why would you when payment by bank deposit is actually worth more than payment by ping as ping incurs fees. There is a large amount of buyers out there still wishing to pay by bank deposit

I don’t mind payment being deducted by ping fees for the item sold but I do not like having to pay ping payment on the postage cost as well.
I feel this is unfair to the seller. Also have noticed NZ Post courier has now downgraded their service on Trade Me from overnight target of 1-2 days for delivery to economy target 2-3 days. 
This evening I rushed two parcels down to the Post Shop due to parcel that was booked to been picked up yesterday still hadn’t been picked again today. This has only happened this week and wonder if this is due to the new changes as well.
Any one else found this happening?