Well, as someone who used to truly hold a purely utilitarian view of bags, I see an inconsistency.
She is wondering if a bag is red enough, and thinking about it after she leaves the store.
Now if you are a utilitarian, you do not do this. You could care less about the color, and if you need a bag, you buy one. If you think it costs too much, you buy another one.
You definitely do not go home and think about a bag you didn't buy, either its price or its redness, and that is true whether the bag in question costs $5000 at a boutique or $5 at the thrift store!
So I suspect that she has more affection for and interest in this particular accessory than she lets on.
I think she's a generally utilitarian person, who is attempting to become 'one of us'! At least on a part-time basis.
That's why she's so insecure about it.
If you've always had no time for a certain item and then, suddenly, decide you want/need it; it can be scary, uncharted territory.
She doesn't want her first foray into handbags to be a complete disaster (and for all the 'purse people' to mock her bad taste/lack of knowledge!) and put her off for life!