^ Whenever I shop outside the US (where I live) I always wonder this. Best to check online first, if they have the prices for things you want and compare. With the poor exchange rate for the US dollar, many things for me aren't less expensive, unless it is a brand that is difficult to find in the US or a brand based in whatever country you are in, like Gerard Darel, Furla, etc.
^^ It is a definite possibility some things will be cheaper with the VAT and the euro trading at a decade low. Depending on when you go the euro could continue to drop even lower or it could bounce back. Check the exchange rates before. And in general French based products will normally be cheaper, foreign products not.