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You need brakes!
Brakes do not count towards the cost of your vehicle as they are considered 'safety equipment' so go nuts if you can. Good breaking allows for better driving.
Band brakes are typically only used on slower cars. If you're a speed demon hellbent on going fast band brakes probably won't work for you. (But if it's your first build and you're mid-paced, they can work.) Lots of people use disc brakes with calipers, and some people do hydraulic brakes.
See Also: Brakes! A more technical discussion
Brake lights are awesome, and actually do help other teams from plowing into your rear end. They are not required, but they are recommended.
(Add links below to various brake solutions)