Even if you don't have big volume/quantity, you still can get a slightly cheaper rate by letting your transporter know the frequency of your delivery. The more frequent your delivery in a week or a month, the better rate you can enquire from your transporter. At the end of the day, it's still up to you whether you want to take the trouble to negotiate RM1 or RM2 cheaper per carton.
Don't look down on the RM1 or RM2 discount, as Malay saying, "sedikit sedikit, lama lama jadi bukit"