I’d stick with Amazon if I were you. All of my Amazon sites only have Amazon affiliate links. If you use Google Adsense display ads on your site, you’re literally taking people away from your site for the sake of just a few cents with these type of ads. If you direct them just to Amazon, then you have a greater chance of earning more money from that click.
Amazon has spent years perfecting the art of online selling and you’ll learn a lot about online marketing by observing how they do it. They constantly test different ways of promoting products and have evolved their site quite a lot over the years. See what widgets they use to promote related products, watch how they use reader reviews, and see the way that they describe products.