I have a few questions before asking for a model and buying it.

hi
I modeled several models from the movie starship troopers (1997) here are the links
https://www.cgtrader.com/3d-models/space/other/starship-troopers-lunar-base
https://www.cgtrader.com/3d-models/military/other/starship-troopers-cannon
https://www.cgtrader.com/3d-models/architectural/other/starship-troopers-port-joe-smith
https://www.cgtrader.com/3d-models/various/various-models/starship-troopers-outpost-whisky
https://www.cgtrader.com/3d-models/aircraft/military/starship-troopers-dropship
https://www.cgtrader.com/3d-models/military/other/starship-troopers-statistical-pazitsiya

and about the violation of rights, I do not know about the value you have to talk to a 3d artist

If you want the model only for personal use, then you should be safe without any permissions, otherwise it would clear infrigement to release it as a game mod, commercial or not, it doesn't matter. I think it should be possible to aquire permission, even if movie itself is very old, but it probably would cost much more than you think :]

Are we talking about payments in dollars or other currency ??