First off, im an amateur when it comes to stereos and jeeps in general. I've got a 2010 sport unlimited with what I assume is the infinity upgrade (because of the sub in the back). I'm looking at the polk db561's for the sound bar and polk db6501's for the front two speakers. I assume I will need an amp upgrade. I would prefer a cheaper amp but whatever gets the job done. All this included is going to be about how much?