Towering... depends. If you go for a case that's designed to hold an A1200, it's getting expensive. That's why I bought a cheap big tower for PC, got a cutting machine from my brother, cut the necessary holes and went with a selfmade solution that costed about 35 Euro for the case and 10 minutes of work with the cutting machine.
Oh, and I spent another 7 Euro on a "Knight Rider"-style running light for the front.
[Edited] Ok, I forgot the adapter that was needed to attach an external PC keyboard. Dunno how much that was.