To be honest, I'd be surprised if someone gave a lot of money for them, especially with missing parts or in half built state. An unopened box maybe.
Thing is with these 50 years old kits is that they are regularly re-released (in case of Tamiya, basically constantly in their catalogue), sometimes by another company, so the one who wants exactly these sprues had many opportunity to get them, those who want the subject, they have loads of newer, higher quality kits to choose from. Especially in the ww2 German topic.