I have been pretty lazy about checking. Lately I check whenever my sis tells me that there is something I'd probably be interested in eh heh. There were a few times I've dumped a dollar or two in to get that a silly badge that takes multiple consecutive crane pulls to get to.
I like the badges that can replace the pre-loaded apps (music, camera, etc) even though the only ones I really use are eshop, settings, and street plaza. There were a few badges I got also to represent particular folders I've made (such as stairs for "the basement," a flag for completed games, etc).
Pokemon Go, and many many board games