Bitmain has been declaring their miners at the purchase price for quite some time now.
If for some unknown reason customs charge more than the percentage for VAT based on the purchase price, you can get that additional money back.
However, do not forget that the carrier ie UPS charges around 10 for the customs service on top.
Its difficult to get such a refund. The first thing is that bitmaintech issues no invoice.
Blockchain info and the order page is the only proof. I doubt whether they will accept it.
Move over its bitcoin and so you need some luck if you are dealing with non-bitcoin friendly officer.
BitMainTech should allow CC/paypal payment from the next sale.