when I was looking at Epson 3800 & Canon 5100 and scouring the net for that information, it all distilled down to APPROX 0.9-1.1 mL per 8.5x11 which is approx A4 or something like 0.012mL/sq-inch
then just turn the math crank regarding cart cost / # mL. An A1 is around 800 sq-in equiv so 800 * 0.012 is 9.5-10mL per A1 print.
a Z3200 seems to cost approx $65/130mL for a $0.50/mL, soooooo, it appears that you'll burn through approx $5 of ink alone per A1. Then
add in paper cost, amortization, etc etc
If the Z3200 is more ink efficient, the number goes down but I suppose the numbers aren't going to be dramatically different.
Actually, I'd be interested in hearing what you come up w/ for a quote. It seems like there is something like a 2-4+x cost multiplier to make it all worthwhile.