
Bagger, we are kind of in the same boat, except that you already have the hot rod!! I had my buddy in the parts dept look up what we would need to convert the standard 4 speaker, with cheap CD radio over to the 6 Disc Infinity setup. The 4 "door Infinities" retail for around $105 each, the 6 Disc unit retails for $760, but I saw it somewheres for around $575. To get the Audio controls on the steering wheel (which is an absolute must to me, I have them on the Dakota now), you have to change the wheel for $170 and add a wiring harness (info is sketchy here) for $240. I had him look up the Auto Dim rear view mirror (again, on the Dakota, hard to live without), it goes for $140 and the wiring $20.
I did this homework, so that if I make the move on the truck I have in mind, I'll try to get them to sell me those components at their cost and roll it into the financed deal. Probably their cost is around $800 - $1000, which isn't bad, considering that is $1200 of options right there from the factory. Yes, it would be much nicer to have it installed at the factory, but the dealers don't seem to agree when they order these things
For your deal, you might want to look aftermarket for 4 kickin speakers and add an Amp to your standard setup. With me, I couldn't live without the Audio controls and I'm not sure that they would work with the standard CD radio, so it will cost some more.