productivity gain from 30-inch monitor?

A researcher has posed that it is worthwhile to get a 30-inch Apple monitor ($1999) because it improves worker productivity.
I really think some researchers are just not that thorough. Yes, you can likely get more work done with more desktop real estate, but how does this compare to a dual monitor setup with, say, 2 17-inch or 19-inch monitors, which would cost far less than $1999? I think unless you need contiguous screenspace (such as with Autocad, Photoshop, or maybe movie editing), the dual or even triple monitor approach is much more worthwhile than one huge single screen.
Do we even need dual monitors? Not necessarily. I currently work on just my laptop screen, although I certainly would make full use of dual monitors like at my last job or at home. As a networking and security geek, I could actually make use of 10 monitors if I had them, displaying things like dashboards, traffic sniffing, alerts, remote control sessions, etc. But for your normal workers, one monitor, maybe two, is sufficient for their job. Eventually, I get into the realm of wanting separate systems as opposed to more desktops or monitors.
I will say, if you want to impress pretty much anyone at work, grab a spare system or two, set it up next to you, and have it running pretty graphs, traces, and dashboards nearby. People seem to think that amazing, even if it is just gibberish. 🙂