No clue what sales would be needed. Classified information, no doubt! Yes, I have considered the kickstarter option, but once you factor in printing, artwork and also a 'salary' for my own time, it gets pricey. Doing a kickstarter really is like publicly putting your neck on the line. The response might be overwhelming and positive, or the total opposite. Anyway, something to be considered for the future.
At the moment, just chuffed and grateful to have Book Three out for people to enjoy. The response has been pretty positive so far, which is great!