what neighborhood is best for shopping with a sixteen year old fashionista , without going on that paris tour for shopping which costs...
I would suggest the Marais. 3rd & 4th arrondissements.
You can go at the 66 on the Champs Elysées, which as a part of thrift shops (great vintage bags over 40 euros...), Le Marais is also a great district, I would sugget you to take the subway until the "Hotel de ville" station, you'll be next the BHV (Commercial mall), and then just walk into the Marais where you'll find many thrifts shops and small designers shops. You can also go to "les Galeries Lafayette" and "Le Printemps" (subway station : Les galeries lafayette-haussman), those are great shops with cheap stuff but also great world-known designers such as chanel and dior (you can have a quick look to that stuff even if you won't buy anything, and if your daughter is into fashion). Email me if you need further details.