I wanted to add one thing to this. Go to a car audio shop and actually listen to the speakers.
Just because they are claimed as being good by someone on the internet, doesnt mean they really are. You wouldnt buy a car at the recommendation of someone on the internet, you would go test drive it first.
Go tell the car audio salesperson what your budget is and have them make a few diffrent recommendations as to what they think would be ok and WHY.