I just checked to see if the apple link worked, and it appears that it doesn't so, go to the apple store, and click on the 'Hot deals' sections. That is where the refurbished and special computer offers are. I wouldn't buy it directly from the apple store though. Too expensive, you can find better deals elsewhere.
If you can afford to wait until at least late November I would suggest doing so. Then check out some of the previous sites mentioned, or even SmallDog.com
Once you have your iBook, jack in some memory. Go here for some of the cheapest memory. My Cube has 1GB of memory, upgraded from 128MB, and it performs smooth. My father upgraded his PowerMac at around the same time and didn't experience memory problems.