He'd saved my life at the cost of his own, and I've carried that burden ever since.
"He saved my life at the cost of his own."
That's like saving £5 now at the cost of having to pay £10 in a years time (to use a simple analogy).
Or just an alliance to save the Empire at the cost of my race?
He'd used it to save her life at the cost of his own.
I can't save myself at the cost of another.
What right have we to save the captain at the cost of his son's life?
Will the politicians decide to save an industry (and a way of life) at the cost to the global economy?
They are beasts, trying to save their lives at the cost of my own.
How could she save her daughter's life at the cost of so many others?