I'll second Momo.  in 1/250 scale, there aren't a lot of off-the-shelf figures or kits of figures.  It's not a common scale. Recently, there have been ship kits released in 1/200 scale, and there are some aftermarket items, including crew figures.  But that one isn't too common, either.  I would look at 3D printing sites like Shapeways, or reach out to forum members, here and in other forums, to see if someone could custom-print figures for you.