Older G's look like a bargain, however they are banned in most of the developed world due to noise, so where are you going to go except shuttle between Kinshasa and Punta del Este ( as long as you land and takeoff in daylight hours on a weekday)
You can't compare a stage II GII with a stage III Challenger.
The Challenger is most likely on an engine program.
There is always more then meets the eye, I love customers like you; more money then sense.