hen I travel abroad, I buy very few items...may $30 worth, so I have never had to deal with import taxes, but I have a question. What if I am in a 3rd world country and buy something for the U.S. equivalent of $100, but in the U.S., a similar item might sell for $1000? Do I declare the amount I paid or the amount it might be worth if I were to sell it in a retail store?

A person also shouldn't have to prove that they had already bought something prior to departure of the trip they are returning from; it's almost as bad as those 3rd world "fines" for minor infractions that are really acts of extortion.