Which GNSS Receiver module fits best

off-the shelf GNSS Receiver modules are nice and small and ready-to-use and allow you to exclude tricky RF layout aspects from your design. DigiKey offers some of them for around 10 EUR. I had a look at various candidates from LINX, STMicroelectronics, TELIT, GNS Electronics, Würth Elektronik, Lantronix and u-blox. See my review here. Maybe it helps you to pick the most appropriate module for your application. Take care, Kersten.