So that we already know what are the cheapest undead and the cheapest orcs lets talk about more modern approach.
What are the cheapest 28 mm "grunts" with guns? Generic, cheap bodies for all of your pulp and sci-fi needs?
I just want a huge swarm of shitty backwater militia for scenario play. Something killed en masse by heroes.
Starting with strong contender, napoleonics from Em4. At 5£ per 20 bodies, even if you cannot find some use for the command, they are probably one of the best deals on the market, but I am sure they can be overshadowed by some chinese green army men.