Just noticed for any Amazon US product, there will be 10% discount on purchase confirmation screen if you use Amazon Business account.
The price will show up as about the same as normal Amazon, unless business discount applies, during the checkout process but you'll see it drops 10% in the last screen where you can press the 'buy' button.
I think it's something about GST & unsure if it's a hack or intended but enjoy!
Didn't work for me. I tried to buy the item from this deal and the price didn't change at checkout- https://www.ozbargain.com.au/node/910112