I have almost talked myself into the 24" Canon. Nice rebates. I have been researching papers and also trying to find out ink cost per print. Yes, I know it depends on coverage, but I haven't got a clue as to the cost per square foot.
I've calculated my raw cost per square inch for ink at around $0.01015 per square inch. That does not include maintenance tank usage, ink used for cleaning, etc. That's all factored into my markup when I charge people for the job.