The package size depends on the country--some have a max length of 40", some 60", etc. My postman gave me a copy of the USPS International Mail Manual so I could get an idea before I ship--saves me a lot of aggravation.
For France, air mail max length is 60", max length and girth combined is 108 inches. For economy parcel post, it drops to 42" and 79" total.
Generally costs me around $40 with insurance to ship a bow to France--it will vary depending on the weight of the package and amount of insurance. So far I haven't had any problems, although customs may hold a package and it seems to depend on what mood the customs official is in as to how much duty the reciever will have to pay.
If the package is longer than 60", expect to pay well over $100 with UPS, and the customer will generally have to pay more also (UPS charges their own duties on top of everything else).
Chad