I wonder about that RTC battery. Remember I'm an electronics designer among other things so I went looking for why a 3V cmos battery would be over a dollar.
https://www.google.com/search?q=P000563990&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjyk7CnqaLVAhWFllQKHQo4AGAQ_AUIDCgD&biw=1536&bih=731
It looks like a classic CR2032 battery in some cases and in others where some prongs were added or a cable. That is possibly why it's more than a dollar. We keep a pack of CR2032's on hand and get them in bulk.
If I ran across one with a cable I can replace the battery and reuse the cable. Little snip snip, solder and electrical tape and I'm done for a dollar.
Call me cheap.
As to the module, let's hope that clears it all up.