Also, this ‘order’ will need to be financed. Where’s the money coming from?
Do you ask the same when other airlines place big orders? Usually their financing is built on a house of cards, with all sorts of byzantine financial instruments propping each other up. Iran Air doesn't have that problem.
Iran has over
$100 billion in oil revenue frozen in various banks around the World. The cessation of sanctions will release the majority of that; Iran has been consistently selling oil to China, Turkey and a host of other countries but because of sanctions the buyers held the payment in escrow.
And then there is the money that the USA seized; a couple of weeks ago Iran received the
first tranche of funds that were trapped in US banks since 1979; $400 million plus
$1.3 billion in interest.