Neubob,
I got them from various aviation week articles over the last few years. It's tough to find a single cost but if you add up various options, that's about what you get.
As an example, if you try to find the cost of a basic F-15E, you might find a number as low as $55 mil. But that's for a -220 engined plane without CFTs or LANTIRN nav/targeting pods. Add the extra for -229 or -129 engines, the latest targeting pods, a V-1, V-2, or V-3 radar, the latest GPS/INS, and the central computer upgrade, you're easily looking at $85mil.
The latest new-build export F-16s with sniper pods, conformal fuel tanks, AESA radar, and the latest EW suite runs about $65 mil.
The global hawk is the same way. Find a price for the global hawk, and you'll see that it doesn't include any sensors. The sensor package costs about as much as the plane itself, so by the time you're done adding it all up you're talking nearly $100 mil each even without ground control stations.
I wish I still had my 2006 aviation week sourcebook because it lists some of this stuff, but I tossed it out after reading the articles.