There are several things that create this price discrepancy, and none of them impugn the quality of the Airmotiv products.
07-08-12: Mechans
Are the amps in the Airmotiv products actually good Hi-Fi amps? (Hi-Fi is my new old term for audiophile level) It's hard to believe they could be good, and the speaker drivers being good at the same time for, that price.
First of all, amplification: General purpose amplifiers have to be built with enough power, current, bandwidth, damping factor, and low enough output impedance to drive a wide variety of speakers with different impedance curves and current demands, and with a bandwidth to cover the full range of human hearing and beyond. In powered speakers, the engineers only have to build an amp that will power those specific speakers well. And for biamped speakers, the amps only have to cover the frequency range of the individual driver they power. So for example, the tweeter drivers don't need big power supplies. Then there's the packaging. Go to a DIY amplifier site and the amplifier module may be $150, but by the time you add a chassis and front plate, the price doubles at least. Built-in amps need no such packaging. Then add in that they are assembled in China and direct-marketed and you are at about 1/4 the price compared to USA manufacture and wholesale/retail distribution.
As for the speakers themselves, ask any speaker maker how much furniture-grade cabinetry adds to the price of his speakers. I used to moonlight with a piano restoration company, and the refinishing of the cabinetry amounted to fully one half the price of the restoration of an old grand piano. Such a piano would get a new pinblock, soundboard, strings, and the keys and action completely disassembled and reworked. Yet stripping and re-finishing the casework cost just as much. With monitor speakers such as the Airmotiv, there is no veneering, no filling, no finishing other than wrapping the enclosure in a black or dark grey synthetic.
Then there's economy of scale when you have bespoke drivers for a large production run. That enables Emotiva to include a ribbon tweeter that might cost $200 on an individual basis from PartsExpress.
Add it all up and Chinese-mf'd direct-marketed monitors in plain-jane enclosures could equal the performance of a $1500 combination of amp and speakers. Reviews of Emotiva products seem to confirm their high level of quality. My latest issue of Stereophile reviewed some of the Emotiva MTM-array floorstanding speaker, and they look to be well damped, linear, and an excellent value.