[edit] Air
http://www.tajikistan-airlines.com/
Munich <-> Dushanbe
Pay at checkin desk in munich, 850 euro, cash
Dushanbe <-> Khujand ($50)
[edit] Train
http://www.seat61.com/Russia.htm
London <-> Cologne = ? Cologne <-> Moscow = ~ £290
Moscow <-> Dushanbe = ~ $400 ($150 each way) -- 4 days on the train