I'm not sure that you'll have much luck with this one, the only pre-paints that come to mind that might fulfil the criteria are from Tannhauser (I think Fantasy Flight still support it). It's an early example of the miniatures board game genre & a good number of figure expansion packs were made.
It's set in a universe where WWI never ended (it's 'now' 1949) so the Germans aren't exactly Nazis, but the uniforms are close enough in this case. The minis are a mixed bunch - some excellent, some... not. You might be better off scouring Ebay for the figures - good luck with the project!