It depend on your country In some country, tax would be 10% from the purchasing amount but usually buyers ask to declare item in low amount and mark as a gift to refuse from killer custom charge. In Australia, buyer will get free charge for purchasing until approx. USD 900.
It doesnt matter where the bag comes from. Customs is worked out where the bag is delivered..I've bought from the UAE and looked at a bag from GBR. The UAE transaction was fine, but the cost for customs from Britain was ridiculous (~$150), so I skipped that. Just ask the seller to find out the customs charges using their shipping method. FOr what it's worth, the UAE bag came FedEx and there was a 1 day delay for paperwork but otherwise everything was very smooth.
Just ask the seller to find out the customs charges using their shipping method.