Another possible new Trait for B&C.

You are Stingy. You don’t like to part with any more money than you can possibly get away with. You may potentially be better at managing your money and tracking your possessions, and possibly less easily tricked by monetary deceptions; but your unwillingness to spend may make you appear selfish, or make you live more uncomfortably than you could afford to.

Another one that might be better treated as a subset of another Trait, such as Principled: Not to Spend Any More than Utterly Necessary. But again, this probably makes a good addition all by itself.

I suppose this could be rephrased as Miserly, Penny-Pinching, or similar, though those would all have slightly different nuances and implications.