You should spend 9 ish on the car, and keep the extra 3 for future maintenance and snow tires. I'm guessing you could get an early 2000's station wagon with decent mileage for that price. Get an AWD wagon with decent gas mileage. It won't turn heads, but you'll get places, and it'll last you a while. If you do set aside some extra cash for maintenance, it'll really come in handy.
I need to start setting aside some money for shit that happens to my car. Sometimes it'd be nice to have a fund.