I had a bit of a search and the best I found is this.http://ask.yahoo.com/20060717.html
Their result is $6,685.92
The number of people is pretty easy to chase up on the American census site. Census.gov
6,760,000,000 and rising.
The more difficult part is how much money. The yahoo answer just adds up how much all the rich people have in total.
The answer that makes sense for me is that money is a rough token to represent "resources" and that depends on what you consider to be a resource. At one time that was just a small number of things that would help sustain life, land, food and a few basic materials. Later it included scarce stuff even if it didn't have a lot of practical use, like Cowrie shells. Now almost everything is a resource. We aren't even a closed system since sunlight is a resource and that keeps on arriving.
So you could say it is almost infinite.
The cool bit is that by finding new uses for things, formally useless stuff becomes a resource, thus creating wealth. So wealth is created by thoughts.
Sorry if that is a bit esoteric but it's a neat idea.
Nick in sunny Southampton, UK