Bski,
I just read this thread and didn't know if you had made a decision on your siding or not, but let me know if you are still looking. I have a pallet (about 19.5 squares) of primed Maxiplank fiber cement siding left over from my house still in the factory wrap. I don't know if that would be enough for your job or if you would have a way to pick it up, but I would sell it to you for way cheaper than what the vinyl would cost you. Let me know if you would be interested.
Thanks for the nudge, bbjr. PM's exchanged...
Post a couple of pics of your project. As I recall, it was gonna be a monster.