I don't think they are making Moto Mods anymore. So the only place to find them is third party sites, like eBay. Remember.....they only said three years of Moto Mods, and we are at the end of Year 3 (2016, 2017 and now 2018).
I think we will see new phones in 2019 that either don't have Moto Mods, or use a different kind of Moto Mod that is new and no longer compatible with the first three generations. That's what they told us all along.....three years.
Sent from my Moto Z (2) using Tapatalk