Just to throw in my sixpennyworth here.

For the last 32 years of my working life I was in senior management of a 260 years old English perfumery house, based in London's West End. The enormous world-wide mail-order business represented a significant part of the company's turnover and, in those days was generated by our glossy paper catalogues - the internet had not, at that time, penetrated our 18th Century HQ in Jermyn Street!

The only workable system of charging for packing and posting was one based on the value of the total order, although the actual postal cost was unrelated to that charge. The charge made for mailing a small bottle of expensive perfume was therefore much higher than a heavy and less expensive box of soaps, but I do not recall ever receiving complaints about the additional costs. It was a system that worked extremely well, especially with mixed orders for several different products, and was one that was easily calculated by our customers at the time they placed their orders.

I have not looked at the KiltStore site recently, but perhaps they do something similar. Just a thought.