How to reduce shipping price from Amazon US

I originally posted this in the Amazon US thread but wanted more people to see it so decided to make a new thread.

As some of you may have realised when trying to pre-order from Amazon US directly, it likes to ship everything individually even when they have the same release date.

I may have found a genius/incredibly stupid way to group those items and save on shipping.

Basically, you'll need to create a Wagga Wagga address in your Amazon account, add whatever you want to pre-order to your cart (might send you to buy it individually, just go back). Once you have everything you want, go to the 'Place your order' screen, change to the Wagga address, change 1 item's shipping speed, change it back and it should be a much better postage cost. Then change the address to the one you actually want to send everything and place your order. Should keep the reduced postage price.

You may be wondering, why Wagga Wagga? I have absolutely no idea. Works with individual pre-orders and potentially in stock items.

Tested further with different locations and only South Albury, which is close to Wagga Wagga, gave me the reduced shipping.