You need to plan and save in advance. Some of the MCAT prep courses give discounts for financial need. Students on financial aid at Columbia should talk to that office about extra loans.
Tuition varies quite enormously.
You must also consider special fees, living costs, whether or not you will need a car. Medical schools will give you comprehensive information about costs. Yes, but not nearly as much as at undergraduate college. They start out expecting you to take a very substantial loan before they even consider grants. You should expect to emerge from medical school with considerable debt.