Would you consider kitbashing some from plastic kits? I'm pretty sure that you could buy some individual sprues of models in tunics, cloaks, and even semi-naked, armed with a mixture of axes, swords, and shields which could all be cut down to make more improvised weapons such as knives, clubs, and small wooden bucklers. Some kits to consider might be:
Wargames Atlantic Dark Age Irish - Lots of bare feet, and you'll need to shave off any broaches, but it's got a good mix of components to get you started, including slings, spears/javelins, clubs (may need trimming), and even some dogs (if you're happy to paint differently so they look less like Irish Hounds).
From Victrix, you have Balearic Slingers, Greek Peltasts, Carthaginian Citizen Infantry, Numidian Infantry, and Unarmoured Samnites. On their own, each is is not quite right, but if you mix and match between them, you should be able to get some great results. They all have a mixture of modest weapons, a few bits of armour/helmets, and lots of togas/tunics/similar light clothing and bare legs. The slingers and Peltasts also have slings.
And Perry Miniatures have the Mahdist Ansar box if you want some suitable models with a bit more ethnic diversity (perhaps as Freemen or escaped slaves?). Again, lots of models that are lightly-dressed and armed with simple weapons. A frame of their Zulus might also be worth considering too, for the torsos, heads, and arms.
Warlord Games, Gripping Beast, and Fireforge may also be a worth a look too for some suitable options.
You should be aware that there is a likelihood of slightly different sizes between the kits, so for example some heads may look big/small on certain other bodies; but if you're prepared to mix them up, you shouldn't have too much difficulty in getting things that look good together. Plastic is easy to cut, and glues well in a strong bond with plastic cement, and so is pretty forgiving to chop around and mix up different kits with to get what you want. Whatever is left on the sprues can got into a box for use on future models/projects.
You can often find sellers on eBay who sell you single frames (they often have lots of different sets, so you can save on shipping if you buy them all from the same seller), and if you're in the UK,
The Sprue Shop also offers this service. I'm sure there are others too.
