Any Monster Kid from the vintage days will remember the "Spook Theatre" trading cards. Also known as "Spook Stories" for the title on the back of the card, we just called them "monster cards". Any Google search will show that many of these survived the years without being destroyed by using them as "flappers" on the spokes of bicycle wheels. Complete sets do run in the hundreds of dollars, but if you're just trying to fill in some missing numbers to your collection and aren't too picky about their condition, you can easily find individual cards selling for five bucks or so.
More expensive, however, are the stickers that came in the wax packs along with the cards. The numbers of these seem to have diminished from being used on notebooks, Pee-Chee folders (so-named for their color, if one is interested to know) or any number of other surfaces. Unlike the cards themselves, they are also prone to being counterfeited for their ease in being reproduced.
Gaudy, lurid and drawn by an unknown artist(s) they are a sight to behold. I'm showing a few examples here, some a little less common than others that I remember getting quite often, as well as the card doubles, triples, etc.