The payouts start around 4% and increases up to 6.5% as you sell more crap. Endless.com shoes pay out 15%, they're a parent program with Amazon. The Amazon cookie lasts only a day, but it's amazing what other crap is purchased even if they don't go for your original product.
I use a combo of adsense and Amazon on my product niche sites. What's nice with Amazon is they supply all the content and photos you need for your site. Overall my Amazon niche sites are getting the standard 2-3% CTR. The adsense does a lot little better. Total them up and it doesn't suck.
What's funny is I started with Amazon affiliate links when I first started, then decided they weren't worth it. (Damn it, I wanted the easy CPA cash NOW!) Randomly sprinkling Amazon links on vaguely targeted websites doesn't work. You've got to target the site to the product, not the other way around.