Shipping charges are the biggest headache for me,I typically spend around $35 at a time (still looking for a go to), lots of vendors dont do 1st class intl(i dont mind the wait),so $12 or so shipping for $35ish of product is a bummer,typically i'll only buy from vendors who'll do 1st class,even that varies a lot,how can it?Some do 1st class for $3,others want $10,shipment weights are virtually identical.
Also,one of the slowest shipments to arrive was a Priority intl package (bumped up from 1st class by vendor),go figure.