Custom system help....

I have recently purchased a Low Rider Tricycle bike and I am building a wooden box for the back which will house a stereo system. I can handle building it but I have no idea how to make the stereo system.

I have some speakers already and I will be purchasing a tape deck. What will be the cheapest way to power this and the most efficient way? What do I need to buy in order for this to work?

I know this is an odd question but thanks for anyone who tries or can help me with this.

You need twelve volts. I'm not exactly sure what a low rider tricycle bike is, but if you can get 12v from the battery and 12v only when it's on it'll act just like a car.

Buying a btery wont do anything it will give you the right power but you need a constant power source to charge it in other words an alternator. By the way you car puts out between 12v when its off and 14v of voltage when its running from the alternator. But you will need a way to recharge the battery.