Thanks for doing the research Cptnodegard. I would definitely go with priority as my experience with first class has been REALLY BAD. I once had a perfectly addressed package go missing for a month!

In regards to duty, I am not sure of the regulations in France. However, when I sold my 770 to a guy in Canada he had me write "repair service" on the customs form and it when through without a hitch. I guess this implies that you already own it.

Found this on USPS:

Priority Mail International
2lbs $24.00

Express Mail International
2lbs $34.75