No offense meant but if you feel that you can't afford to maintain a car you really shouldn't be considering the purchase.
If the tires supplied on the car are half way decent you should expect, at least, 45,000 miles before you have to purchase new ones. At 15,000 miles per year you should get three years out of the tires.If those tires cost $125 each to replace you are looking at a total of $500 to replace those tires. If they last you three years all you need to do is save $3.21 each week and at the end of those three years you will have the $500 you need to purchase new tires.
Now, lets talk about the brakes.