You can quite easily build a drone capable of flying for many miles with a 2.7kg Payload for 2-3K. Indeed $10,000 would buy you a very, very nice setup. If they wanted to go the plane route a Mugin will do 15kg and still be under 10k [1]
Yup, that would do it. 600km range for 15kg of 'cargo'. Assuming a full write-off of the air frame in the flight, possible recovery of the auto-pilot/electronics. It's right on the edge of what its radar profile is going to look like. (model/bird vs small aircraft).
Anyone know what that's based off? A "full sized" drone of maybe 3-4X this size, but with exactly this profile flew directly overhead at low altitude about 18 months back.
[1] http://www.fpvmodel.com/super-huge-mugin-4450mm-uav-h-t-tail...