Hard agree with this first point.
However, I hate to seem like a misery guts on this thread, but depending on what you know about her shopping even a voucher for these shops is risky. A lot of young people are strongly into slow fashion - buying very infrequently, buying second-hand, buying from specific stores that meet their specific ethical criteria....
If I'm struggling for something to buy I normally try and go for something consumable. Nice hair mask, good chocolates, bottle of rum, candle... something that will very likely be used.