You can skimp out on a bunch of things as a new hire. Take my advice... spend a bit more and get a good flight case and overnight bag. You don't have to get a top of the line model, but spend more than the bare minimum- otherwise you'll probably be looking for something before the year is out. (And odds are that you could end up spending more in the long run).

I've flown with more than one pilot who had a bag or flightcase come apart in the middle of a trip. It really sucks to have to finish out a 4 day carrying your stuff around in one of these: