First of all, I'm no expert. That said, I've been lurking for a handful of years...so until someone more knowledgeable than me posts up, this will give you lots to think about:
If that rig was for sale on mud, no way it would bring $9000 unless more detailed build/condition info was available, including photos prior to paint to confirm body condition. Also missing is undercarriage pics for rust check, leak check, etc...
With that ad on craigslist, I see it MAYBE going for more in the $5-6000 range, especially if there is a buyer comes along who is not worried about who has done the maintenance/mods/paint.
If shortcuts or poor workmanship are evident, I would even say $3500-4000 or even less may be more reasonable given the length/cost of a to do and redo list.
If the seller had a reputable shop do the work and has receipts and more photos and build info, $9000 may not be outta the question. If an enthusiast/expert performed all the work on that rig and can explain it front to back, including what's currently needed (they all need somethings given their age and price range), then I might be talked up a bit from the $6000.