Would it be dumb to buy a car after my permit ? ?

If all you have is a "permit" (a restricted learner's license), you can't take title to an automobile and you can't insure and register an automobile. Even if you could 'buy' a car with only a 'permit', you still wouldn't be able to drive it. 

Sure, Martell, go buy a car.  Fine by us.

However, since you are not yet a license holder you will have to have someone who is willing to register and insure the automobile.

Who might this person be?  

Only currently registered and insured vehicles can be used for a behind the wheel driving test.  

Yes. You can buy the car, but you can't be insured without a license. So you'll have to insure someone else if you plan to drive it before getting the license.

You do not need a drivers license to buy or title a vehicle.

Where do people get these false notions ?

You will not legally to drive the vehicle until you get your permit, and you will need a licensed driver to ride beside you; but you can buy, title and register a vehicle without needing a license or even a permit.

Don't your parents have a car? Use theirs.