If you want to use a sub, I would recommend to get an amplifier too. If you are not going to do it, than ....
Front Speakers Infinity Kappa 63.7i or 9i
Rear Speakers, if u gonna have the lows going to the subwoofer than I'd recommend Infinity Kappa 693.7i or 9i
Good head unit for the money is a Pioneer any of these would do. I own two of these myself, work great.
http://www.pioneerelectronics.com/PUSA/Products/CarAudioVideo/Source/CD-Players#Home
As for the sub it depends on you, and u should get an AMP....
Front + Rear speakers would be around $200 - $250
Head Unit would be $150 - $250
Good luck with a subwoofer and amplifier. (Since its a budjet system a perfect sub will do almost the same as a cheap sub. Just make sure it handles the lows well)
Good luck.
