I think you have to spend another $400-500K to bring to its full glory (FIKI, updated avionics, etc). But then you may have a $1.2 mln aircraft. Sounds like a very good deal.
Regrettably, it's not as simple as that. This plane has several significant issues.
This is an Avidyne Eclipse, non-ETT, one of the very small number of planes remaining in the category (most of the 38 built like this have been upgraded). Eclipse Aerospace (who took over the assets of bankrupt Eclipse Aviation) stopped supporting these planes as of March 31, 2013. You can still get them worked on, but there are some parts unique to these planes that are no longer available.
As you noted, it's not FIKI. It also has no GPS for navigation (the ad says it has GPS, but you can't navigate with it), and it's limited by AD to 30,000 feet.
You can fix the 30,000 foot limitation, but you can't just pay a little money to make the plane FIKI. It can only become FIKI through a major upgrade that would entail adding new tip tanks and other structural modifications as well as removing the avionics and replacing them with all new ones. I believe they're not offering that upgrade any more (though maybe they'd do a special deal for it). When it was last offered, as I recall it was over $1 million because it is such a big upgrade.
The Eclipse is a great plane, but the fleet suffers from having several different versions, and that makes it tough for a potential buyer to know what he's getting without assistance from somebody that really knows these planes. This is a bit of a "gotcha" plane in that regard.
All that said, these early un-upgraded Eclipse 500's represent an amazing value for the right buyer who can understand and work around the limitations of an un-upgraded Eclipse. Where else can you get a personal jet with just 100 hours on it that burns about as much fuel mile per mile as a twin Cessna and pay only a half million for it?
Ken