Below $2000 for any System 11 with no significant defects is a good deal IMO.
If the playfield is damaged, sure, it should be sub $1,000. But for a nice one, I'd generally pay up to $2,000 for a machine I want. You have to consider how hard it is to find a machine from 25 years ago that hasn't taken a beating. Both those CL posts seem good (though there is often a problem that's not so obvious from the photos, and that's when it's time to haggle or walk).
Of course, Chicago is one of the first cities to get pinflated. Every machine is more expensive here. A seller in another area may have a great price but no buyers! A wise seller in those areas would stay firm on the price and lug the machine to expo if it doesn't sell.