[ShagginJet]

You're looking to spend about 40-70 for the average pair of speakers. As for the sub/amp/box, some people have package deals starting around 150-175 for an 8"/10" and about 150 watts of power. To do it right, expect to spend 400 or so for the sub/box/amp, and about 120-150 a pair for the door and rear deck speakers.