The problem I see is that they are useless out of combat. They don't drive the second SRV or whatever.
In this game money is easy to come by, I would prefer them to be more useful and possibly a way to use all three at the same time (faster scanning, improved turret fire, internal damage control...).
The cheapskate method is hire crew do the mission sack the crew then cash in. It means you are limited to who's on offer though.
Or don't worry about the space-cash.