I went to one of the boutiques there over a week ago and didn't find that it was necessarily that much cheaper. The value of the dollar is low there. You might be able to save in taxes, if you're a not a European citizen.
The selection was not that much different from what you find at Neiman Marcus or Saks or Barneys, etc. I noticed only a few differences in what they had available. I actually left the store empty handed.
Not likely, considering the exchange rate of the $ versus the Euro. Sales in France run twice a year in February and August, and called "Les Soldes", so you may or may not find Loubous on sale. Having lived in Paris for 2 years, I never ever saw a pair of price reduced Loubous.
However, Saks and Niemans put them on sale all the time...In fact, I just bought a pair of the silver Altaritas for my wedding in October for $298! You can find a better deal here I think...Paris may be the better place for vintage Loubous which wouldn't be easy to find in the US.