Depending on what and how you want to do this. I am one of many that a couple years ago switched to the Polk DB651 inboard speakers. Personally to me it was a very dramatic change in sound quality. One that to this day i still get complimented on. I changed out my head unit to allow for more external out puts etc which the original head unit did not. I went with a Alpine Digital 5 channel amp, which was similar money to Kicker 5 channel, maybe slightly less and i went with the sealed Kicker Sub unit which for me sounds great.

I had and or have no intentions to have tower speakers as most music i/we listen to is during down time between ski sets etc. This system ROCKS yet was pretty budget minded, being slightly more than what your start point is. For me its all i want and need, yet still can be modified.

Like everything just a matter of how much you want and how much you are willing to spend. Go in steps and enjoy. Tons of good info and advice on here , take advantage and Good luck.