I'll answer this, because I gladly paid a decent sum for mine. I paid a premium (maybe the most anyone has yet paid?), and I won't say what the price was, but it was well over $500.00. I also threw in more money because I got the exact fish I wanted.
More and more people are getting them off live food, which should suggests better growth and health. I know mine eats shrimp with cichlid pellets stuffed into them, and he has great color on the gill plate and fin area. I also was very successful in bringing him back to health from a bad accident that another forum member also went through, and his armatus died. I have to think mine is extremely healthy with the diet he is on.
Also, the fish that have been imported thus far are also starting to get larger, and since really only two shipments have come in with them, all those fish are at least 10 inches or so now. I'd say they are comparable to Goliath African Tigerfish, but way more volatile. The most aggressive Tigerfish species is Vittatus. The record weight for armatus is ~40 pounds, and I don't know what the record length is.
You might thank me for contributing for the sudden price spike, but you have to witness this fish's temperament and no-bull**** attitude. Like someone else said, I could shoot a gun off next to my tank and the fish wouldn't budge.
[EDIT] After reading Trev's post, I agree that size is a big issue regarding price. I would never pay what I paid for a small fish. Mine was ~12 inches when I got him. Dieselmack just gave away a 13 inch armatus for $250.00, which is nuts, but he pretty much had to get rid of it.