Hey guys, I'm extremely tight on money but I want to do SOMETHING to my speakers to improve their sound a little bit. I listen to a lot of metal, so I was interested in swapping out the speakers for something more decent than stock, but I also listen to a lot of electronica/dubstep/rap, so I thought adding subs would be a good idea too. However adding subs usually entails adding a new amp too, amirite? And it's expensive to add subs/amp AND new regular speakers - I'd probably want to stick to only one of those upgrades in the interest of saving money.
My budget is really tight - I'm a stupid broke teenager left penniless paying for a recent accident (not my fault, mind you

) so I'll probably ask for one of these upgrades for christmas. That means it's gotta be really cheap, as in no more than a couple hundred dollars - I'd say my budget would probably be less than $200 if that's possible.
I only know a little bit as far as speaker wiring and car audio go, so I'm not exactly sure what I should be looking for. (actually, speaking of that, does anyone know of any good articles or sites where total noobs can learn about those types of things?) I don't care about trunk space, so putting subs in there would be no problem, although subs as big as that would probably be expensive anyway :x Any suggestions?