An auto insurance policy is a legally binding contract, and most laws prohibit someone under the age of 18 from entering into a legal agreement without the consent of an adult. The exception to this rule is when the 17 year old boy is emancipated, meaning he is responsible for his own financial welfare. In this case, a 17 year old could buy auto insurance, but would still pay the costs associated with getting car insurance for young drivers.
Teen drivers are recognized as the riskiest drivers on the roads, and the rates they are charged by insurance companies reflect that. In most cases, it would be far less expensive for a parent or guardian to add the teen driver to an existing auto insurance policy than it would be to pay for a policy for that driver. Since adding the teen to an existing policy modifies the risks involved, the increase in premiums is relatively low. This is because the insurance company is not insuring the vehicle solely as a teen's car, but as a car which is shared with the teen on a part-time basis. Even so, the original policy premiums could go up by double or more.
An emancipated 17 year old boy would be able to purchase a car insurance policy directly, but since the car would also be registered to the teen, he would have to pay the full premiums for his age range and driving background. Premiums could be as high or higher than the cost of the car payments, especially after GAP coverage and all other requirements of the financing agent have been met.
If you must purchase a policy as a 17 year old, it will be financially important to qualify for as many discounts as possible. Look for discounts for taking a driver's education course, or ask about limited mileage discounts that lower your rates in exchange for keeping your driving time to a minimum. In addition to discounts, consider paying cash for an older vehicle, because that will allow you to drop comprehensive, collision, and GAP insurance coverage.