Lifes savings...Whose money was it?

It was Muir's retirement money.

Duncan would have presumed the operation was a legit CIA operation, so he would have likely assumed that the money came along with the operation. So his comment is ironic, because it is in fact his (Muir's) money.

Yes, Duncan expects Muir's using covert funds: after he says that, there's a shot of Muir, showing that under normal circumstances it wouldn't be Muir's money: he lets out an inaudible sigh.

51depasser

Muir's, and i'm taking the movie at its word that he didn't have anything else, or he wouldn't have had to bargain down so low, and that if he just had bags of money it wouldn't have been a sacrifice. Plus, he keeps looking at his retirement dream, which he then gives up, undoing the wrong he did bishop in the first place.

There's no indication that he was anything other than a good soldier, so I don't think he embezzled operation funds way back when.

This was Muir's money. This was the money he told Bishop to put away "..so you can die somewhere warm. And don't touch it for anybody, EVER." Muir broke his own rule because he used it to get Bishop & Hadley out of prison. This is also the reason he had to get bargain basement price on this. He knew he had to use his own $$.