Many seller offer combine postage if you buy more than one item. These will encourage buyer to buy more items.

And, buyers want to save postage, so, many of them ask for postage discount before them bid. But, for more reason, the postage does not change and the buyer has already paid the order. So...NO postage was saved!

Most of the sellers do not allow buyer to change the amount of unit price and postage, so buyers can not combine postage themself. Of cause, seller can create a combine postage rule, but if the sell thing with difference postage, it is hard to do that.

How to save postage when you buy more than one item?

Firstly, ask if there is a postage discount or not.
Secondly, buy the items you want.
Next, ask the seller a total amount of your orders,
Fourthly, wait until the seller send you the combine/new invoice from ebay.
Finally, you can pay it.

Pls note: do not pay until you receive the combine invoice.