It's often still cheaper to buy from Amazon than buying from vendors, unless you scour the internet for the 30% off coupon and sign up for the newsletter for the 10% welcome bonus and then promptly report the newsletter as spam.

There should be some kind of federal law against needing to do this.

Buying direct from vendor should always be the cheapest, and at least 5% cheaper than Amazon (since everything on Amazon is automatically 5% off)