You can get a GPS module on aliexpress for around $6, whereas an ESP8266 is <$2....

lorenzhs on May 26, 2016 | parent | context | favorite | on: Warwalking WiFi Networks with ESP8266 IoT Module

You can get a GPS module on aliexpress for around $6, whereas an ESP8266 is <$2. So it's still very affordable, but GPS is quite a bit more complicated than WiFi and correspondingly more expensive.