Should i buy a new car, or fix what i already have? (car buying experenced people needed!)?

okay, so my power steering is out on my car (88 plymouth sundance) and itll cost 700 dollars to fix it...right now i live home alone with my mom and pay no bills (im 17) should i just fix my car that is a hunk of crap, or put 1500 down on a car? the price of the car wouldnt be more than 5 thousand dollars, and i figure i could pay it off while im home and dont have bills, so i have a dependable car in the future... but i dont want to be in debt or pay secret hidden thousand dollars through buying a car like this. should i just fix it and wait till im 18 to buy a car (by then ill have enough just to put all cash down) and establish credit, or should i go get a car right now?