Never used that particular one, but I have used some of Microstrain's
units. (If I remember correctly, they were worth a couple thousand dollars about 5 years ago.)
They're similar internally to the sensor boards we use in FRC, with the exception that they have an on-board processor providing significant built-in filtering and communications (via RS-232, and USB on the newer ones). You're paying for the filtering and calibration when you get one of these. In an application like a UAV, the extra cost is justified, because your AHRS sensor makes your autopilot work—you can't afford to have spurious readings.