Used aircraft prices

[Unknown98]

How do the prices look on used aircraft? Too expensive, not expensive enough...? I just sort of quickly came up with a price formula based off age. That will need to be amended to take into account cycles (and/or hours, miles) I'm sure. A very old aircraft with low miles should be more expensive than a very old aircraft with massive miles.

I also need to go through and add when production started for each aircraft, not just when it ended. That way I can accurately generate used aircraft with a range of different ages.