Staurt over at http://strangemagic.robertsongames.com/2011/10/big-thrills-with-cheap-monsters.html
Mentions a good point about using rubber monsters for minis.

I am always on the lookout for new beasties for my mini collection.
Some of the repurposed items i have are
Bag of bugs
Tube of horses
Party grab bag butterflys (some with wings removed make great giant ants)
My sculpity stuff
Rubber dinosaurs
Mage knight figs , DC hero figs , Dream blade figs WoW figs ...etc here is a pic of part of my mini cupboard.

I found a bag of reptiles crocs lizards frogs etc... i am slowly repainting to look less like cheap plastic (bottom right)
I forgot the Heroquest set of furnature and monsters. 

Above pic is the right hand side of the cupboard.. now the center...thats the bottom...

Thats the top....

This is the upper right section and below it...

The sculpity section.  The rat bases are casino chips with heroquest rats added

So remember you can find minis in most toy sections... dollar stores usually have plenty of rubber monster bags.