i make low poly characters specially to be used for games so i make a high detailed texture that will stay the same or lite l deference when using any render plugin .
i use default scan-line for the characters , but mental ray and vray are both are amassing for realistic images .
i use mental ray for the commercials , fast and high quality .
hope this was helpful :)
regarding money and the cost of vray , you can download it for free
take care