One of my collections is that of many sets that appeal to me. The list of completed sets there stands at 538, though set sizes range from a 1 card "subset" to a 1320-card multiple-series issue. The "sets wanted" portion of that collection is an additional 148 sets now. One of my goals this year is to get that down to 125 sets, but I'm not making that any easier by finding more sets to collect.
I didn't scan them - they're too thick to fit through my sheetfed scanner - but I have four cards from 2016 Topps WWE Undisputed. These four are from the Divas Revolution insert set, not to be confused with the Divas Revolution release. At 30 cards, and apparently not easily found, I don't think I'll be finishing this insert set this year.
All of the cards mentioned here were picked up at Card Fanatic, an independent card shop in Shibuya. They do carry Japanese cards, but it appears that they can be a good source of random American cards too. Card Fanatic isn't really a "singles" shop, though. They have some showcases with nice cards at high prices and a couple dozen 5000-count boxes with soccer, NBA, MLB, Japanese baseball, and other random cards. Visitors to Card Fanatic are more likely to be pack and box busters and memorabilia collectors. Those box busters do dump their unwanted singles on the shop, which leave them some stock for singles collectors.