If my items are not free shipping to start with, or bundled into a buy as many of this item as you want for XXX amount type of shipping offer, I offer half off shipping if you purchase more than one item?  The highest shipping cost for any item you purchase will be full price.  After that all others will be discounted fifty percent!  This can make a tremendous difference in the cost of your purchase.

  Let me give an example: you win three books at $5.00 each with free postage.  Your cost is $15.00 right?  Now, buy those same three books from me at $2.99 each and pay my postage.  Without the discounts you will pay $7.80 in postage, or a total of $16.77 for the same three books. 

Factor in the shipping discount and you will now pay only $14.17 for the same three books you just "got a great deal" on in auction!