IMO, it's best to look around muna. Audition as many setups as you want before you buy so that you have a better idea on the system you want. If possible look for car audio old timers. It's a learning experience as well as a hobby to the enthusiast.
Read around the different forums/message boards so that you're not limited to the information available.
Also, fight the urge to purchase car audio items to fill-in temporarily for what you really want based from your auditions. It will cost you more in the long run.