In England this is slang for 'what'll it cost me'?
The damage of conflict through history has always been great, but one has to imagine that at some point, some clever warrior started looking at better ways of gaining resources than just running head on at the enemy and seeing who came out on top. Ways to lessen the damage, yet still win the fight.
Stealth and ambush come to mind as very ancient hunting tactics, as surprise stacks the deck very much in your favor. Fighting with a plan, in units, as pairs or more, also highly effective. And of course deception - using guile and understanding of human psychology to manipulate your opponents into traps of your making.
Dueling with swords is in essence a Monkey Dance not resource predation, but fails that description in one crucial way - Monkey Dances are not meant to be fatal, they are about status.
George Silver in his 'Paradoxes of Defense' in 1599 bemoans the deaths caused by dueling. Kings and military commanders have banned it over the centuries due to it's high casualty rate as the confusion between wanting to fight 'for honor', but making the mistake of using lethal weapons has killed off many of the best warriors of each generation.
You still see this confusion nowadays in the sword play martial artists do, as we try to understand the blade - most fights end up with both people damaged or dead.
I personally think this is a problem, this 'learning to die' thing. It is certainly a step on the way to understanding, but there is a step beyond that, the hardest one to reach of course, and that is the one where you get to walk away afterwards.
I see very little in systems about the 'exit'. A great deal of time is spent on the stuff in range - what to do after engagement, some time is spent on entries, but where is the part about 'getting away'?
I know it's possible, Musashi showed that it was about 400 years ago when medical help was not an option. You may say that he chose his opponents so he always had an advantage ... but maybe that tells you something ......?
George Silver himself lived to a ripe old age, as did plenty of skilled warriors back in the day. Who did they fight? How did they win? When did they decide not to fight?
Obviously hard to say, but I suspect this idea of walking away afterwards played into their tactics as much as how to enter, and how to engage.
What'll it cost me? - As little as possible please.