In an interview to Glamour magazine, Knightley said that she splurges if she wants anything but tries to stick to her budget.
"I think living an (expensive) lifestyle means you can't hang out with people who don't live that lifestyle," the 29-year-old star said.
"It alienates you. Some of my best most hilarious times have been in the least luxurious places.
"I mean, if I want or need something that goes over that, I get it, but, yes, around that," she said.