The iMac configurations currently available are already a very good deal.
Now if you're willing to wait for the next revision, you might be able to take advantage of closeout prices on the current models, but you could be waiting
until spring.
If your budget is tight, then it's probably best for you to wait until Apple releases the OS X 10.5 Leopard models.
We should all know more about that release date at MWSF in January.