Check out the issues of Motor Trader. If I am not mistaken, I saw a couple of shops advertising it there. Do note it will have to be replica only as the original M3 bodykit will not be able to fit the standard E9x models due to the wider wheel arches.
There are a couple of shops along the same row as H Performance in Sunway which sells the kit. Can't remember the price they quoted but it's the same row as H Performance and the row behind Coffee 51