The cost doesn't come from the number of barrels, they're a really high end company making them one at a time by hand.. I've seen Nighthawk Custom 1911's in that price range that only had one barrel. Be cool to see what one of the el cheapo manufacturers like Rock Island could sell one for.
Practicality wise......I want to laugh at it but a double tap with one trigger pull ain't no joke.
Probably a little on the heavy side the the form factor is still reasonable. Definitely not a concealed carry piece but would ride fine in a drop leg holster. It's only .45 ACP so recoil is controllable once you get used to it.
One thing I wonder about--when you fire two rounds simultaneously side by side like that, does it affect accuracy?. I'm thinking along the lines of air cavitation and stuff like that.
Biggest issue--it fires more than one round with each pull of the trigger.......I bet the the fucking assholes at the BATF would make you do NFA registration on it.

"Know thyself, know thy enemy. A thousand battles, a thousand victories."
--Sun Tzu