Student discount - hardly more than 5 - 7 % off, unless your school has some sort of special group purchase.
Don't get the ram from apple. It's super easy to change it yourself. I would say get the cheapest MacBook, and buy yourself a pair of 1Gb RAM modules. That's a cheap computer, which will competely satisfy your needs. Then, if you really want to take a big loan, buy yourself an external hard drive to store all this music you'll be recording, an external monitor, to display plugins while your macbook shows the mixer, buy a better microphone, interface, etc. The computer will be outdated in two years anyway, and this one will suffice to your needs, so put the money where it matters, that is the sound equipment which doesn't change as fast and will make a big difference. At current speeds, for this kind of application, a difference of 0.5GHz is just not worth the money, whereas the RAM is crucial.