If you do the work yourself, you can start with a complete tear-down before buying anything. That way if you find a real show-stopper like the bottom bracket shell threads are trashed or the headset is shot and you can't find a replacement with a short enough stack height (that happened to me with an old Trek.) you can give up the project with no money lost. If the needed replacement parts are cheap enough you can decide if it's worth continuing.
I agree, the project isn't worth the money a bike shop would have to charge for labor and parts.