The actual goods? The cost of running said robots would need to be covered as well.
Energy and materials.
The robots can do anything a person can do. Including getting whatever resources needed to make renewable energy and build solar panels, wind turbines, nuclear reactors, batteries.
They can mine for metal ores, melt it, pick cotton, plant potatoes, sew buttons, fix other robots, you get the point.
designing them.
Ok I didn't really think of that. I was assuming that the stuff that we have today is good enough and if everything was free there wouldn't be a demand for innovation.
Plus I'm thinking now the biggest expense of trying out new things is building custom made stuff or trying new formulas... That a robot can do, it just needs a person to tell it what to do.
Look up Ray Kurzweil and Singularity.
I scanned the Wikipedia article for a bit. I'll look at it later a little more. I saw he holds of that things keep on getting better forever which I don't see any reason to believe so.
+1. Resources are still mostly finite. More robots would generally accelerate that process through increased consumption.
Ok that's also a very good point that I didn't really think of. I was assuming that there would be enough for everyone which I guess I shouldn't have.