No, not usually.

Apple usually charges a premium for their RAM, and using 3rd party vendors is much more cost-effective. Here in North America at least it always seems like if you buy RAM through Apple you're paying through the nose. Can't speak regarding Oz though of course.
What exactly are you looking at in terms of a RAM upgrade through Apple? Just curious what the details are... Because keep in mind that an upgrade from 1 GB to 2 GB (as an example) is not simply the price difference between the two options - you should factor in the fact that the initial cost of the 2x512 MB RAM sticks is built into the cost of the machine. So technically, you are buying two 1 GB sticks of RAM from Apple as an "upgrade", however do not get to keep the two 512 MB sticks which initially came with your machine. Follow me?