Its the same when I get stuff fom the US sent to Canada. If Customs thinks that you bought it as a retail item, they will charge you for Duty. If you get the person sending it to mark it as a gift, then Customs can't charge you.
Wait till you try send something out of UK then, bigger than 30cm x 30cm x 30cm they double the price of it.
a mask to the USA signed for used to cost me around the £18 mark ( $40 ish ) my last mask i sent out cost me £40 which is $80, ( add another £10 for signed for insured) all because they reduced the SMALL PARCEL size limit.
we screwed on the way in and now on the way out.
No wonder they just call us BRITAIN now, we're no longer GREAT.