One advice I could give you is, keep an eye on second hand market.
I've seen real bargains.
There was once a Blizzard 060/ppc240 going for around 70£!!!!! SCSI was reported to not work, but hey talk about a real bargain! :-o
Don't hold your breath for one of those though, that's the biggest one I've seen ever.
So what BIG bargains have you guys seen?