.....Something in the program costs more, therefore the government buys fewer of them, therefore the unit price goes up..... ...until a coutry decides it's all getting too much and pulls out, therefore the unit cost goes up, therefore...
which is exactly the problem for many customers. If you tell LM that you limit is $xbn, then that's what they will charge. The variables are then how many jets you will get and what capabilities are included.
It seems you are either in and have to suck up whatever cost is forced on you to achieve your desired operational capability, or you are out. If the latter, it's a bit of a bind for the remaining customers who are then faced with the conundrum, only it just got a bit worse. Only governments can get themselves into such a fix. They really are the very last people you should give your money too. Only problem is that are alive to that one and don't give you any option - unless you are able to chose the jurisdiction to pay your taxes in.
The F35 programme is long past the point of being financially redeemable. If it had been a European project it would have collapsed years ago. There would not have been the collective will to have kept it above water. I think it will still survive but at the literal expense of huge costs, small unit numbers and initial poor performance. It has been a political play for some time now, and military capability is a side-show. It may eventually perform well, but that will happen because it has to once it's in service, otherwise you've thrown away the $bns spent so far. It's what you have so it's what you have to use.
LF