Alright, so I got the Unrealscript thing working (which means the Deus Ex vending machine code is Like That because...somebody went "ah, fuck it, that works and that's all it needs to do" and fair enough).
So I have a vending machine that can vend any spawnable item! At a map-design-time-settable price per unit!
Now to try to create a mesh for it that the Unreal engine doesn't shrug at and treat a random half of the polys as invisible. Looks like a BSP problem? Which the collected wisdom of shitty sneering teenager Unreal mappers from forums that died a decade ago assures me doesn't happen with static meshes. Joy!