Stuff I have collected for use over the years-
Megabloks dragons that come in eggs. Wal-mart and K-mart have/had them. Multiple colors and designs. Sizes Large to Garg.
Cheap DnD / Monster figure packs that can be found at dollar stores and Rite Aid drug stores. Have dragons, cages (perfect for figures) and small walls and ruins.
Plastic fantasy and "real life" animals I get at the local book store and Michaels art / craft supply stores. Recently I got a "huge" sized 4 headed 3e Hydra, a 2-headed green dragon and dire sharks and Garg scorpion. Prices are between 4 and 15 dollars. That is where that huge minotaur was found. I've been meaning to buy him but seem to always get a dragon instead.
Hard to get now but- Yu-Gi-Oh figurines.
McFarlane dragons
Other Sci-Fi and Horror figures. One had a black wolf of Huge size which I keep.
Hero / Horror clix (got a Predator Horror box set coming)
Starwars miniatures.... I like the creatures and use some of the less known jedi / sith as Kalashar people for Eberron games
and I'm sure I'll think of other stuff in a bit.