I recently bought a Sony head unit for about $135 got it installed free (some promo they were doing) and it is great!!
I used to use an iTrip and got sick of switching stations on long drives, the sound quality is sooo much better, I just have an input wire running off the back of the unit and into my glove compartment, I keep the Ipod in the glove and just use the controls on the radio to change it!!
Best investment I have made in a long time!!