I have to admit to being a little confused.  After the buyer said to me that the cost of postage depended on whether or not I paid by paypal or DD I said I fail to see what influence PP or DD would have over Australia Post.  The answer I got was this: "Paypal makes us do registered & they charge fees on postage & full payment".

This is a new one on me both as a buyer and a seller so wanted to get an opinion from someone else as I had a look on PayPal and couldn't find where this was.