This one guy made a really popular Android Wear watch face that mimicked the Pixel lockscreen. It only cost a few bucks, and people loved it. Due to some personal things in his life, he had to sell the app to a new developer to make ends meet. The new developer then started charging something like $7/WEEK subscription for a watchface that he didn't even develop in the first place, and runs entirely locally on the device so it's not like he's maintaining any servers or anything.