I can't say enough good things about my Sony CDX-MP70 Head unit. Nice big control knobs for my old arthritic hands, seven customizable equalizers, really cool slide out CD loading tray, seven different colors available on the display, MP3 CD playback capability (about 125 songs on ONE CD!) AND an AUX input for my iPod. Lots of clean power too. I ran the head unit without an amp for a couple of weeks and could've left it like that forever and been very happy. Turning on the DSO (Dynamic Soundstage Organizer) function was like adding component speakers - it really adds warmth and reality to vocals coming from low mounted speakers. Now that I added component speakers I don't use it - it makes the tweeters a little too bright.
I agree with Hack about getting what you pay for. I personally have liked Polk speakers for a long time - in the house or car- and that's what's all around (except the sub, which was a clearance bargain). Alpine, Infinity, Boston Acoustics, and mbQuart all make fine speakers too, and with the adjustments available on the Sony you'd probably get good performance out of any of them. Go somewhere between 150 to 200 for a pair of 6x9's for the back and 110 to 150 for some 6.5 coax's for the front.
This package should run around a grand installed. After you get some more cash you can run an amp and sub out the seperate sub channel RCA's in back of the Sony. Oh, yeah - the sony has adjustable high and low pass functions (78 or 125hz for either) and a sub level control, too.