Judging by the pictures. (ive seen this tut before) its not that accurate. You may be able to get a resolution of about 10 thou. Not accurate at all and will have a noticable gap or the inlays won't fit.
I'm looking into building somthing with a resolution of approximately .002 , Well thats the target anyway. To keep any kind of accuracy you will need linear slides on every axis and ball screws for the feed. Talkin big $.
Controller/motors(with enough power, printer motors won't cut it) $450
Linear slides off of ebay about $400 for 3 axis.
Rolled ballscrews $300
Materials and other odds and ends $300
Not cheap by any stretch of the imagination. Sure you can build a cnc for under $500 but it will not be that accurate. A little too inacurate for guitar building. (usable for cutting rough shapes like balsa airplane parts)