Here is a short durian tutorial by Mr Wong who runs a small boutique durian stall at 231 East Coast Road (Opp Jago Close) Singapore. You can contact him for your durian needs by calling 97514828. At the time of blogging, his Mao Shan Wang was selling for $16 per kg. Having been in the durian trade for 20 years, he has established a good relationship with his suppliers who would pre-select all his durians so that his customers can look forward to a really good durian experience.
Source: http://ieatishootipost.sg/2008/07/durian-tutorial-made-possible-with-my.html