I am a bit skeptical as it covers all bands with "no tuning."
As qrp-gaijin notes, it's a shorted turn acting like a voltage probe. The balanced amp makes electrically induced noise common-mode. The Moebius loop doesn't seem to make a big difference over the competition (according to the Clifton Labs tests), and I didn't see any patents listed, so there's no new art here. With such low radiation resistance, most of the cost probably goes into making low-ohmic-resistance, weather-resistant connections to the loop. The preamp should be a piece of cake. A CATV transistor like the 2N5109 would do for most of the gain, and a FET input stage would handle impedance transformation.
Note that the preamp uses 20 V (for high IMD performance) at 240 mA, or nearly 5 W. That correlates with a high-current bipolar amp stage. I'm sure you could duplicate this antenna for a lot less than $400.