For standard shipping, the heavy weight surcharge is $8, and for faster shipping is $10. Anything more than 5 pounds heavy will be charged. If Amazon listed the weight wrongly, you can inform them and they will refund you the surcharge fees.
The surcharge is mentioned in the guide above.
You can still cancel your order and see if it's selling cheaper at Book Depository.
@Anonymous
Your book probably incurred a heavy weight surcharge.
E.g. $5 (box) + $5 (per item) + $8 (weight surcharge).
For standard shipping, the heavy weight surcharge is $8, and for faster shipping is $10. Anything more than 5 pounds heavy will be charged. If Amazon listed the weight wrongly, you can inform them and they will refund you the surcharge fees.
The surcharge is mentioned in the guide above.
You can still cancel your order and see if it's selling cheaper at Book Depository.