Hi, Not many people here keep venomous snakes; not many people keep herps at all. You can try your luck at http://petshop.8m.net ; go to the "Reptile Board". They have some people there who are selling/buying venomous snakes. You may be able to contact them.
P.S The herpers here keep snakes which they find or catch. Some people import corns, milks and kings as well(albeit illegally). The reticulated python is rather common in Singapore and in fat is considered a pest by chicken and duck farmers.