Around The World For £4,000

The previous post regarding the ultimate train (and Ferry) trip got me thinking if it is possible to go around the World by land and sea, just how much would it cost?
Using very rough Google searches and translating pages, the figure is around £4025 but that is an extremely rough search of ferry and train companies.
The first leg is straight forward, a Eurostar train under the Channel from London to Paris on the Eurostar (£69). 
From Paris to Moscow will cost £362 on Rail Europe and then a payment of £550 will take you from Moscow to Beijing via the Trans-Siberian Railway and Trans Mongolian Railway.
Once in Beijing the trip begins to become less straightforward. There is a train that will take you from Beijing, through North Korea to South Korea which costs £69 but North Korea is not the stablest of places so whether the train is running or Kim Jong Un and his band of merry men will let Westerners through his country is another thing so you may have to catch a ferry around to South Korea for roughly the same price.   
Once in South Korea there is a joint Ferry, Rail ticket you can buy for £194 that not only takes you across the Sea of Japan but lets you travel from the Southern tip of Japan to Tokyo where you find yourself pondering how you are going to cross the Pacific to America.   
The only ship i could find to make the trip was a cool £1500 and lands in Seattle which is a bit annoying as i was hoping to do the route 66 thing up to Chicago but there is an Amtrak train that crosses from Western USA to New York in the East for £280.
New York to Europe is another problem as there is not a regular service across the Atlantic except the so Queen Mary 2 cruise ship so its a deep dig for £1000 and a week or so later you end up in Southampton and back in Blighty. 

Around the World for approximately £4000 with the costs of crossing the Oceans bumping the price up unless you could cadge a lift on a merchant ship and offer to work your passage by cooking or swabbing the decks.