I buy 95% of all my bags from overseas. I agree that for Chloe or B-bags you are better off trying to stick to buying from EU countries as you wont get taxed on those high end prices but if you can find a good deal in the US then it might be worth looking into. Just make sure that the seller states the value that you actually paid on the shipping forms and NOT the retail value or you will be over-charged on customs duty.
^^^ That's about 25-30% which is a good rule of thumb for working out charges.
I've had bags marked "Used" and "Gift" before but still got charged customs. Then I have had items marked the exact same way and got the 30% charges I really think it's pot luck if it gets through the system and you don't get charged duties....