Matters what features you're looking for in the HU. If you don't plan on adding amps for your speakers in the future then just look for speakers that match your HU power wise. Can't really give an estimate without knowing what features you're looking for and how much power you want. Shop around online and you can get a sense of the price range. I paid $350 for my HU (Crutchfield sells it for $500 those bastards) but that's definitely a more expensive one, got it cause it pushes out 60W RMS per channel which is the highest I've seen on any unit. It all depends on what you're looking for. Keep asking questions.