After visiting several markets reputed to carry Malay products, I found Shun Fat in Monterey Park had the best selection. It carries various brands of Malaysian-style curry powder, the fermented shrimp preparations belacan and petis udang , and spicy sambals , as well as the necessary dry spices for curry and the rice noodle soup, laksa . Most items are in the Indonesian section, but some are found in a separate curry section along with the general seasonings.
In the "wet" department you'll find lengkuas , (the ginger-like rhizome known as galangal in English), lemon grass and Asian basil.
Shun Fat Supermarket, 421 N. Atlantic Blvd., Monterey Park. (818) 308-9880.