The question was posted as to what link should be given on personal websites and other self-marketing materials in regards to purchasing a copy of your book. I am going to suggest that you use Amazon as the primary link for people who are interested in buying. You can use your personal site for media queries and other such needs. Matter of fact, I would even recommend that you link to your Amazon page from your own website. Here's why:
1. Amazon's recommendation and pairing system is the best of any online retailer. In other words, the more people purchase your book from Amazon (or even visit the page), the more likely your book will start showing up in the recommendations section of other book pages or in their computer generated emails.
2. Amazon will help you sell your book if your sales are high enough. The rankings are calculated hourly so the reality is, if you do an event that triggers a dozen people to buy your book and they all do it via Amazon, your sales rankings will shoot up. When your sales rankings shoot up, your book gets matched with other products.
The fact is, Amazon's setup will do far more for you and will do it in an automated manner, than any other site including your own. In the long run, purchases from Amazon will serve you the best.