Yes I use affiliate marketing at my day time job. Nearly 40% of our sales come from affiliates. I am also readying to setup the same for my startup. I am planning to offer 50% of our sales because we don't have any operating costs, but in most cases the payout is around 30%. Note that to make your AM successful you will need to constantaly come up with new offers, incentives, banner ads etc... and communicate with your top earners. Make them happy.