I have three solutions to minis:
1) for monsters, check out the toy section of the dollar store. Look for tubes of children's animals and dinosaurs, etc... I also found a local "gift shop" that specializes in odd stuff - they have plastic toys for between .25 and 1.00 - centipedes, snakes, spiders, turtles, etc... that work perfectly.
2) polymer clay - I've modeled my own simple stand-up counters, and have made elementals, treasure chests, altars, and other furnishings, oozes and blobs, even trees and such. I have an idea for doing a whole bridge and a wagon, too.
3) the standard dice, with each number turned up to represent a different mook.