Look around a little. You can find a new G4 1.25 dual processor for cheap, or better yet get a refurb from Apple or an Apple dealer. At the Apple store they are $1399.
http://store.apple.com/1-800-MY-APPLE/WebObjects/AppleStore.woa/71301/wo/0s...,57 I bought one a few weeks ago for $1199 by shopping around. Add a refurb monitor and some RAM (search Ramseeker.com) and you're set. Much better solution than either of your other choices. I've also seen G5 1.6 models as low as $1799 (The 1.8 is a much better value however). The Apple refurb's come with a warranty and are checked out. While it's possible to get a bad one (like anything), I've had great success with them over the years.
Tony!
