He bought the assets of the company, and you sir would be considered a liability, it is a legal issue and he has no obligations to you, however I do agree that he should be the nice guy and help you out in some way, shape of form
which this man did do he offered 20% off, as i see it that is very fair. he wont make much if anything on this sale after manufacturing, handling boxing and shipping this small order. yep very fair for someone that is not legally responsible for the plane you bought from someone else.