Where do you get all that oil for deep-frying?

I recently learned that some people in America will use oil to deep fry in a pan to make meals from home, and not just for fast food?

I live in NZ and cooking oil, even the cheap ones, cost a billion dollars. Does half the meal cost come from the oil or is it really cheap for you guys? What do you do with all the left-over oil? Does it feel wasteful?

This sounds judgy but I promise its not, I only mean it to be inquisitive. I'm so fascinated by inches of oil in a pan just for some chicken.