kill for

would/could kill for (something)

A hyperbolic expression of one's intense desire to have or do something. Man, I could kill for some of my mom's homemade spaghetti right about now. I'm so jealous—I'd kill for a chance to go to Brazil for a month!
See also: could, for, kill
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

kill for something

Sl. to be willing to go to extremes to get something that one really wants or needs. (An exaggeration.) I could kill for a cold beer.
See also: for, kill
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
See also:
References in classic literature ?
He will frighten every head of game within ten miles, and I--I have to kill for two, these days."
If you will kill for me the Wicked Witch of the West, I will bestow upon you a great many brains, and such good brains that you will be the wisest man in all the Land of Oz."
And Tiger-Face, also, made another man to be his right arm, and to give commands, and to kill for him.
For instance, the first kill for an American-flown P-51 came over Dieppe in 1942 when Hollis Hills scored against an FW-190 in an RAF Mustang.