Buyer complains about postage price

[SueDonim]

I just made up a dummy example to see if maybe things have changed. For a small parcel TM quoted Aramex the cheapest locally ($6.45 v. NZPost $6.80) but I wouldn't use Aramex anyway. For the rest of the options NZP was $4.80-$9.80 for both islands and TM was $10.17 same island v. $11.43 other island. The $4.80 NZP option doesn't include pickup but the others do. This was just one sample. It might be different for bigger sizes - I know that a NI v. SI differential applies to bigger parcels but I've still found NZP direct to be cheaper than TM in the past.

Maybe you get a TM discount if you are In Trade.

When I'm listing something I always find the box/bag/other packing I intend to use and work out the freight costs first so that I can put in on the auction. That costs time, but no more time than doing it later would take, assuming that I'm going to get a sale. High volume sellers would know how much each size of box costs to send so I'm sure it works better for them to put the information on the auction at the start.

That's interesting, I've never really used it for parcels that small, I always assumed it was cheaper to use mailer bags that are prepaid and choose the appropriate size.
Maybe larger parcels cost less on TM instead, the weird thing is in some cases aramex is cheaper than nz post and vice versa.

I'm the opposite - have occasionally used mailer bags for very small items, but never for larger ones. I see it as buying a bag then paying for postage on top of that. A padded bag for an occasional item might be better than buying a roll of bubblewrap as you have just done, but like you, I did that once and years later am still using it up. I use kitchen ziplock bags to make a parcel weatherproof. Or rubbish bags if the ziplocks aren't big enough.