Seperately those SoB minis are webstore exclusives.
The old Starship Troopers plastic aliens (Arachnid) might be a good option if you can find them (they came 20 to a starter box):


You could do some Maelstrom's Edge minis (hard plastic on sprue):


First is the Minnows $6.50 per 2
Second is the Adult Angel $9 each
Only available through the pledge manager if you were a KS backer.
Certainly not cheap, but the winged ones could make for a terrifying Riddick-esque scenario!
Malifaux has some interestingly scarry monsters on sprue, but those could be very expensive to get a horde of 50 of...
Although these are interesting:

Void Wretches $21 for three, I said it was expensive stuff ($15.75 through MM).
Confrontation: Creatures of Dirz - Phemera Alpha Unit Box (

$12 through miniaturesmarket (OOP)

Now for the bendy Reaper Bones stuff:



All three are $3.99 each, probably cheaper from some online stores (Miniaturemarket $2.99 each)...

$3.29


$2.79 each
This would be quite funny:

$2.29
The advantage of the bendy stuff is price and you can chuck them in a bag.