Other used Mti-10 are going for 700-1000 so this is a great deal.

Xsens' MTi-10 Series Sensors are 5th Generation MTis that set the industry standard for reliable MEMS based AHRS, VRU and IMUs. The MTi-10 series gives the systems integrator a choice of three different integration levels (IMU, VRU or AHRS). The MTi 10-series and the high performance MTi 100-series share a common range of mechanical, electrical and communication/API interfaces to enable easy integration across a wide range of 3D motion tracking requirements.