How expensive is a sound system for a car?

stereo deck good brand usually 150 - 200 $, amplifier 200 - 500 watts 200$ , subwoofer in a box 10 inch prolly 250$, wiring including remote,power,ground,and rca cables probly 100 when you getthe whole thing installed PROFESSIONALLY at a store. OR ELSE BUY USED

A good amp cost about a dollar a watt. So a 500 watt amp should be around $500. But It up to you spend what ever you can afford.