From what I've heard, Ibanez won't sell their necks as parts. They will replace a broken neck if you send the whole guitar to them - this applies all the way across the range, from the GAXs to the JEMs. They also charge a fortune.

You could look at http://www.warmoth.com - they can make you a neck with the same profile, a wide choice of woods, inlays and frets - including stainless steel frets (yum). Probably cheaper than Ibanez too.