What makes a particular item popular as a collectible at any given time?

babie_boomah asked: Thirty years ago everyone wanted Depression glass. Now you can’t give it away. People that come to my tag sales are now asking for sports or military memorabilia, coins, comic books and old fishing lures. Why are these such hot collectibles now?

How to tell if old memorabilia/misc. stuff is worth anything?

Anne S asked: We are going through our basement and have all sorts of old items (i.e. board games, puzzles, figurines, sporting equipment, etc.) Before we throw them out, we want to make sure that they are not valuable. Do you have any recommendations on how to decide what to hang on to [...]

where is the best place to buy Baseball Hobby packs online?

jason asked: there are no card or sports memorabilia shops around here, any suggestions
(other than ebay)
been there already