I just went and bought a new screen for my PowerBook G4 today!
Now all I have to do is wait 3-4 days. Finally, I'll be able to use it as a laptop, except I don't have a battery…
You definitely can.
The shop where I bought my HD from has a stack of 68-pin and 80-pin 9.1 GB SCSI hard drives for $5 each and I bet you can find them for that much somewhere …