Saved myself 10%, here's how:
I ordered the first set with one email address, and then after confirmation, it gave me the option to send an email to 'friends' for 10% off what I just ordered. I sent the email to another 'friend' with an email address and password that I knew, and that had an account with Amazon with the same CC #. Ordered the set for 10% off with that email in the 'friends' account, and cancelled the original order.