Hello,
I am interested in learning the SigFox network, but I can not find a cheap module. Arduino MKRFOX1200 seems very expensive, There are wifi modules and GPRS modules for less than 10 euros. Is not there something similar for Sigfox?
You must have a strange idea of "very expensive". At € 35 (in the Arduino store) it's even cheaper than the Zero and by far cheaper than the other already available SigFox module that DigiKey offers.
The Arduino MKR FOX 1200 even offers a 2 year subscription for the SigFox network. I have no clue what value this represents because SigFox don't provide any prices for the network usage yet (or they hide that effective that I haven't found it).
WiFi and GPRS are available for about 20 years now. Once SigFox is 20 years old you might also get cheaper boards...