Brian - I don't know why you only pay $4 postage from Iherb because all international postage from Iherb to the UK is about $25. This applies even when I place an order for just one item in an emergency. For example I placed an order for magnesium of a type that I can not get in the Uk costing $12.16. The DHL international postage was $24.28, just double the cost of my order!!!
Using other couriers would cost almost the same and I prefer DHL. This seems ridiculous but I have no choice.

Tony