Hello.  Ive been working on car stereos for quite some time now and ive learned a thing or two from all of my projects.  First of all, even if you do not want to have the loudest or the best, do not buy cheap products.  Will you save money?  Yes.   Will you be pleased with the quality?  Not at all.  Spend the money to get quality products.  Don't go nuts but do not be too thrifty.  The old saying,  "You get what you pay for" holds true.  All of this goes for the wiring you use as well.  If you have top of the line components but junky wires, your stuff wont sound very good.  As far as brands go... DB Drive subs are extremely worth the money and will leave you speechless.  Audiobahn amps are unparalleled and can pump out way more juice than they say.  Kenwood subs are great..especially for the low prices.  MTX makes great mid-price speakers and amps and even better high-end products.  JL subs are really nice, but when you buy them, you are paying for the name.  As far as wires go, stinger and street wires are the best.  For interior speakers, go Blaupunkt or infinity.  Dynomat makes everything sound a lot better.  To make all of this stuf work together, you will need a good head unit.  Panasonics and kenwoods seem to be the best for your money.  Overall, sony stuff is not what its crakced up to be.