Relay or Timer??

I got a small motor, like one out of a remote control car. It runs off of a 6 volt battery. When you turn the switch on, it comes on and stays on (like it is suppose to do). But, I want to put a relay or timer in it that would make it run for 15 seconds and then shut off for 5 seconds. Then when the 5 seconds is up, it will come back on for another 15 seconds. How can I accomplish this and would it be expensive???

Nope, a 555 timer with a transistor would work just fine. If someone doesn't beat me to it I'll put up a schematic later.

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Vcc = 6V, t1 = 15 sec, t2 = 5 sec, C = 10µF, Diode = 1N4001,
Ra = 750 KΩ (721.5 KΩ), Rb = 1.5 MΩ (1.415 MΩ)