Check out this awesome series of interchangeable creatures I discovered at a local toy store - Zoomorphs!
I've seen them up close and they are the perfect size for being considered rather large creatures to your standard gaming mini, about a inch or two tall and two or three inches long (depending upon construction). While not super cheap, they are certainly less expensive then most metal miniatures of monsters of a similar size. They also seem pretty rugged as they are designed to be played with by kids 4 and up.
Now go grab Raggi's Random Esoteric Creature Generator and have a blast!
Done say I never gave you nothing OSR.