This looks like a really good plan. It is tempting although I'd prefer a RTW at these prices. The cost is £3,750 a person, about $7,350, at $1.99 to the pound.
There are also other overland excursions as quoted from the New York Times:
"Intrepid Travel is an Australian tourism company that is offering a 130-day trip from Singapore to Paris called To the End of the Earth and Back. Once in Singapore, travelers will journey by bus, boat, rickshaws, trains and even elephants through Asia (above) and will take the Trans Mongolian Express from Beijing to Moscow. Travelers will spend one night in a Mongolian ger, a type of tent, and all other nights in hotels or with local families. The trip's price starts at $12,410 a person (plus $1,300 in local payments); www.intrepidtravel.com/endearth. "