If you get a minute can you run through costs
Well, there are no hidden costs, so it's the cost of the Triplehead box, a GTX 260, and the three monitors.
You don't have a wide choice of Triplehead suppliers, and the week I cracked the only place that had it in stock (the newer digital version) charged me £226 delivered, which was a fair bit more than I could've paid if I'd been more patient. I made myself do an extra day at work that week as punishment. :->
My old 320Mb 8800GTS proved surprisingly capable in most sims (cpu limited, remember) but when switching from the 'mix & match' 4:3 setup to 3*widescreen I decided more pixel power was advisable. I got the (old style) GTX 260 for £160. Oh, and unless something's changed recently, to run 3x(1680x1050) you need an Nvidia card. ATI can't quite handle the total resolution. The widescreen gaming forum's the best place to research this topic.
The monitors were the hard part. In the end I paid 3*£117 for the Samsung 2032BW screens. They're not monitors I'd be happy with on my main desktop box (this machine where I 'live' has a Dell 1600x1200 which is definitely superior in price and quality) but for gaming, which is all that end of the desk gets used for, those Samsungs are excellent.
Oh, I lied... I made my recent iRacing
movie on that machine. Movie editing on a three screen setup was absolutely superb. All the necessary tools and windows could be spread out nicely. I also tried the Eve Online demo recently, and that also benefited from several screens. There are more menus in that game than in all the restaurants in London!
Anyway, it's obviously not a cheap setup even if it compares well to historical gaming costs. And it has limited use in most games, so it's important not to get caught up in techno-lust.

This won't make you a better pilot or driver, but the extra peripheral vision can be useful when overtaking, and the sense of being there is obviously worth its weight in gold. I suppose multiplayer FPS gaming might have some advantages as well.
But the Triplehead does add another layer of complication to the PC, and it can be a pain at times. So it's not a totally win-win situation. You also have to consider what happens if/when one screen dies... even if it's replaced under warranty, the chances of getting an identical replacement may be limited, ruining the uniformity.
All in all it probably makes no sense whatsoever. But then this is gaming we're talking about... since when did that have anything to do with sense?
Andrew McP
PS Don't forget the desk space required and OTT geek factor... this kind of setup takes some explaining to visitors!
PPS The softTH route if definitely worth researching if anyone has a PC with two PCI-E slots.