This paper presents a comparison between the VN-300 and LMS6DSOX + LIS3MDL inertial sensors. The former is a sophisticated inertial navigation system (INS) with applications in avionics and shipping, and the latter are low-cost micro-electro-mechanical systems (MEMS) sensors of 15 dollars. The comparison is performed through the Allan-variance technique to determine: the stochastic noise profile and the advantages and disadvantages of both sensors. In addition, the authors implement for the low-cost sensor an open-source attitude and heading reference system (AHRS) assisted by a Kalman filter for attitude determination. Finally, the paper compares the Euler angles between both navigation systems to determine whether the proposed low-cost device is a reliable Inertial Measurement Unit (IMU).