>>17: Well, yes and no. The system software install discs are separate from the "extra goodies" install discs, so if I wanted to reinstall just the OS without the extra goodies, I could do so (and vice-versa). And I just tested it out... both sets of discs are pretty "dumb" when it comes to customizing the installation, whereas standard OS X install discs are not. With how (in)frequently I reinstall the system, though, I really don't find it much of an issue.
Note that this is the case for my Powerbook. Things might be different for the consumer-targeted mini.
One of the few things I miss about college are the student discounts. :D (I paid ~US$75 for OS upgrades with the discount.) However, Apple sometimes has some good refurb deals on their website too (that's how I got this Powerbook).