I manufacture and sell one unique product. I started with direct sales, doing okay, but it was clear that Amazon is where the real action is, so I tried to sell there. Getting the listing up was a slow and painful experience due to horrible seller service (this is typical). Finally it's listed. Around 15% of revenue is fees. That's with me doing my own fulfillment! Hardly any sales at first, so I had no choice but to advertise. It looks like another 15% of revenue will end up going to amazon ads. Amazon will probably end up making more money than me, just for being the middle man. That's if I'm lucky, because sales are still just a trickle, and I'll probably have to up my ad spend to get any real traction. It seems like the system is designed to put comparable products competing against each other and the one that rises to the top is he one that Amazon can squeeze the most blood out of, unrelated to what the user might benefit from. It's www.bettergeiger.com if you're curious.