I would like to introduce GPS-GLONASS module with optional magnetometer. Major benefits of using those mixed GNSS modules is fast and accurate position fix, because it use both constellation of satellites to predict position.
It supports 3 types of I2C magnetometers from different manufacturers: most popular HMC5883, MAG3110 and MMC3140. Magnetometer on module allow to mount it in magnetic clean place, far away from fields from power wires.
Module has supercapacitor to keep for few minutes backup voltage for GNSS chipset. It allow fast fix after battery change in plane or copter. Connector has raster 0,1" is easy to mount. Crimping tool can be the same as servos.
Boards are available in our shop. Worldwide shipment is only 2,6 Euro.
Documentation, technical data and sample code with magnetometers support, can be found on GPS-GLONASS module with magnetometer website.