if you're comfortable shopping on the web, you're off to a good start. yes, most times in car audio the term "you get what you pay for" is applicable, but if you do you homework, you can get good quality stuff and discounted prices (as stated by feeney). stick to mid to high end brands and try to get good prices and you'll have a solid system without breaking bank.

and the companies i listed earlier will give you the most bang for your buck. oh, and let me add the image dynamics as an awesome value sq sub.