itunes backup suggestions

I use a Mac mini with an 1TB iomega external hard drive using firewire. I want to be sure that I have the iomega all backed up. What do you suggest?

Apple Time Capsule looks great but at 1TB it seems like to much money for something that will be used up soon.

Apple Airport Extreme with a inexpensive 2TB drive

or can I just use another iomenga Mini max hooked up to the current one via firewire and be done with it? These drives are so inexpensive..

Thoughts?