There's always ebay, but I would definitely agree with the guy who said crutchfield. They want like $200 or something for one, but you can get two for around $300. You pay maybe $50 more than you would somewhere else and you get in return the crazy-awesome Crutchfield support and of course, the fatass warranty.
I'd normally say steer clear from the guys simply because of outrageous pricing, but they really have a hell of a deal on those Kappa Perfects. The things sound nice - if I were still going to get them, that's who I'd give my money to.