I'm in the midst of the same project. I just installed a Kenwood 2032 head unit ($129 from Crutchfield). It's a decent unit with all the features I was looking for, but the sound improvement just didn't knock my socks off. I'm pulling it today to exchange it for an Alpine deck. Either the 9846 or 9856. Probably the 9856 if I can find a cable that will allow me to retain control over my stock cd changer.

Kenwood might be right for you, but just wanted to report one dissatisfied customer. Crutchfield is great to deal with, btw. Expensive, but excellent customer service. They suggested the exchange and even pay the return shipping. Can't beat that.

After you've done the head unit and speakers you'll probably want to fill out the bass. Once you've got the music coming through loud and clear, adding something for the low frequencies has a remarkable effect. Everything just sounds soooo much better. I can recommend a small powered sub like this Kenwood. Plenty of bass without rattling the mirrors and can usually be found on eBay for less than $100.

 

Now that I have a better idea of what I can do on a budget, it's time to go see what's on sale I'll chime back in after I order the components. Thanks again to all of you for the help.