Crutchfield has a nice Clarion headunit with AUX input and 4-channel preamp outputs (front, rear) for 79.99$.
It will costs $133.95 all accessories included, delivered to your door (Macomb, Illinois).
Headunit, wiring harness, antenna adapter, dash receiver kit...everything that you need to do a clean install.
I'd start with this, or something similar, if it was me. They have 6x units at this price, make your choice.
Clarion CZ109 CD receiver @ Crutchfield.com
They too had a nice Kenwood unit+front speakers set for a damn good price but it's unluckily out of stock.
Kenwood Receiver and Speakers Package @ Crutchfield.com
EDIT: I forgot that Crutchfield give you all the accessories for free with the purchase of a unit of 129.99$ and +. So since the installation gear alone worth 43$, maybe you should look at a better unit. 'Cause the math says that 80$ for the cheap unit + 43$ of installation stuff = 123$. For 7$ more you'll get a better unit + free installation gear. You'll also get free shipping on top of that.
This one looks good to me:
Clarion CZ209 CD + Ipod receiver @ Crutchfield