The man who wrote the web page said he "That first trip in 1990 lasted two and one-half months and cost $2300, including airfare to London and the return from Athens. I met dozens of people, some of whom I traveled with and got to know fairly well. I became slightly serious about my French, and at one point was able to communicate in a foreign language for the first time in my life. I went to many of the greatest art and cultural museums in the world. I saw the City of Light. I wandered the Acropolis. And as I stood outside Socrates' cell I thought to myself over and over, "How can this be?" 

It would coast a bit more now because of the rise in the coast of living. So I am thinking that it would coast me around $4000 or $4500 I hope that it would be as cheap as it was for him to do. I am also wanting my trip to start in the same place I want it to start in London and end in Tibet so I am thinking it will coast a bit more. His coast less because he only went to Athens   I am still in the planing stage for my trip. 

I think if you want to try this one day take a look at this site http://artoftravel.com