Best price I found so far:

Nippon Water Based Sealent/Primer: RM160 for 20L
Matex White Ceiling: RM60 18L
ICI Weathershield: RM270-300*(for new color range) for 20L

Although most hardware shop have 20L pack (trade/project size) not every shop carry a broad range.

This shop called GST hardware in Bandar Puteri and OKR (near Brother Accs around Petaling Utama) carry a lot of trade/project size color selection. This help to save at least 20% off when you buy in bulk.