I'd probably leave (and have left) my purse in the car regardless of price. To me, it's more a matter of habit than anything, except possibly a sense of trust, feeling safe in your neighborhood. I do it all the time around home or frequent haunts...like school or friends houses, etc. I see cell phones, i pods, in cars all the time. Many times, people think they'll be right back out, or they have their hands full with shopping bags, or kids or the like.
This is not peculiar to me, one bit. Again, I know PLENTY of people that leave their purses in their cars, locked or unlocked. I know the same number that leave their doors unlocked. Cary has the perception of being a safe place...kind of like it's own camelot. Those of us that live here have to admit this.