>>96575747
To simplify stuff, WGA has plastic WW1/WW2, medieval, and sci-fi stuff kitbashing, so you can save on shipping from ordering from the same location. Their Iron Core makes for good machine armour bases.

Additionally/Alternatively for plastics, Perry Miniatures medieval stuff (knights in particular), Northstar Miniatures has Cultist kits which work well (their Frostgrave and some of the Stargrave lines might be useful too), and maybe some of the Warlord Games stuff (I'm personally unfamiliar with their kits, but they have medieval and WW2 stuff and some Weird War 2 stuff in their Konflikt 47 line).

Also, Reaper Miniatures. It's PVC plastic, but it's cheap as tits so you can pick up and chop up a monster or two without breaking the bank.