Regarding where to buy, give NAMA a call. I’m not making an “Irish economy” joke. Seriously, they actually have more planes/helicopters/jets than most people would believe.
NAMA would have got these assets via the banks, I believe the banks were actually quite switched on when valuing such stuff offered by defaulting developers against debts. Tales of N reg machines in particular being offered with major deficiencies in service history abound...
Caveat Emptor.