Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Don't buy a G5. They are no longer supported and they no longer run modern software. Not unless you have an interest in legacy machines (I keep a G4 around for that reason, but my primary machines are all Intel.)
 
If you are willing to try monkeying with it a bit. You could install a new screen yourself for between $80 and $200 (it depends on the model of Macbook).

Though it may look daunting it really is not too difficult. You just need to follow instructions, remove some screws, cables and a bezel. When removing screws label them with masking tape with the step numbers. Or you can lay them out in the order removed (which is what I do).

If the screen is busted and you are going to pitch it what have you got to lose?

Edit: There are also plenty of companies online I have seen advertised as doing the install for $99 just mail them the new screen and Macbook. I never tried them as I do repairs myself. Ebay is by far the cheapest source for new panels.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.