All of these stickers came from various places and at various times. I won’t state whether they’re official or not, simply because there’s a BOAT LOAD of them. I MAY edit the information so that you can get some info when you hover over them, but if there’s nothing during the hover, there’s just nothing.
The best place to look for stickers is probably in an Artist Alley, Ebay, or Livejournal. Most vendors don’t carry them anymore.