I all depends on what you are marketing w/ Amazon. It is a good source to see what niches are popular to go after.
As far as the payout, it depends on the sales volume you generate. Their commission structure is based on a performance factor...meaning that each month the % is reset and you must try to maintain the sales volume in order to get a higher percentage.
They do offer a flat commision rate which is 4% or so, but who wants that.
If you promote their "
endless.com" products, I believe you can get up to 15%.
I currently avg about 6.5% with them, of course, I'm only promoting thru social site & with Google adwords...as my budget is limited.
Overall, I am happen with them as they always paid on time, offer a wide variety of widgets,links, options to promote products and has a very low "Refund" rate.
Be careful with using their name when promoting, read their TOS carefully as to what keywords you can't use. I learn this the hard way and have loss some commissions.