You'll be hard pressed to find a decent running car for $400. But check out craigslist and your local classifieds.

have you tried craigslist.org? Do you have craigslist where you are?

Unless you've the tools and equipment to fix it up, you'd probably do just as well to light that $400.00 on fire. Any car you get for that much is going to be extremely high mileage, beat up, etc., if at all possible it would be better to save up some more money and buy a better car outright or even take the $400.00 as a downpayment on something better.