Step 1: Parts you need!
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1pcs Raspberry Pi Model A or B (Model A is cheaper and uses less USB power). 30$
1pcs SD 4Gb (the better SD card you use the quicker it boots). 8$
1pcs short USB to Micro USB cable. 3$
1psc USB WIFI dongle (check that it works with Raspberry Pi/Linux). 15$
1pcs 24V cigarette lighter USB converter. Note the 24V! Must Be 24V. 15$
1pcs Cigarette lighter contact for chassie assembly. 6$
1pcs 3.5mm female audio stereo connector for chassie assemby. 3$
1pcs 3.5mm male to male audio stereo cable 1 m. 3$
1pcs 3.5mm male male audio stereo connector - short angled. 3$
0.5 m 2 wire cable for power. 1$
0.5 m 3 wire cable for power. 1$