Importing duties and fees are the responsibility of the buyer. Be sure before agreeing to purchase an item that requires international shipping, that you are familiar with your country's customs, taxes and importing laws.
Import duties and taxes will generally be collected by your courier prior to delivering your package.
In the US, there should not be import duties or taxes for items valued under $800usd. Also if an item was originally manufactured into the US (e.g. a Fender American Stratocaster) there should not be any duties when it is re-imported into the United States.
In Australia, there generally should not be import duties or taxes for items valued under $1,000aud.
In Canada, there generally should not be import duties or taxes for items valued under $20cad.
Europe has a variety of VAT and Duty thresholds - you can find a calculator here.
Please note this information changes often and may be out of date. It is for reference only and you should research and confirm any duties or taxes prior to completing your order.