I know that a while back, Sangennaru had some 15mm robots printed. Maybe ask him how the experience went?
From what I recall it was a bit of a mess getting them trough the Shapeways approval system. I have a batch of them and while I like the design the texture of the Shapeways models isn't really to my liking.
As for my own SLS (resin) printer, I think the old saying about pictures will do:
Those drones are direct prints, only some paint on it (not even primed XD) so yes, it can be done.
The knights in the middle here are 6mm infantry, also paint on print.
And because I can't get enough of it, here is a 6mm tank, also a print.
In the end though what Scurv said is key here. Printing is a tool, and you still need somebody to do the design, unless you have specific models in mind that are available for free online. This is a step a lot of people seem to forget about. There are a lot of people out there who appear to be under the impression 3d printer ownership is reason for designer to render all their hard work upon them for free, which is a bit bonkers.
Anyhow, I would say depending on what you are looking for that yes, there is a grey area where printing might be cheaper, though probably not by much. If you are looking for a one of model hand sculpt or 3d print will cost the same, but variable by sculpter. If you want a lot of a specific model having it cast will always be cheaper. But there is an inbetween zone where if you want say a dozen of a specific model printing might be cheaper than having a mould done up.