Could anyone tell me what a "throw out" card is? I have seen quite a few of them for sale from the past generations. Is it a card they would just throw out in the audience?

What a magician tokens from? Just a souvenir from a shop or did these have some type of purpose?

And lastly, are there any publications on magic ephemera? Or even general price guides like they have on depressions glass or comic books.

"Throw-out cards" are also sometimes referred to as "scaling cards". They are souvenir cards magicians would throw, or "scale", out to members of the audience. I have seen some Thurston scaling cards going for about $75