Wim,
With the US, would it be easier to get a friend there to buy it for you and then send it over? That way the supplier doesn't need to worry about the whole "sending overseas" issue, but rather they just send it to someone in the US... who then sends it on to you. Or are there phytosantiary issues that are a problem? I buy some things at times here in Australia for a friend in the UK. A lot of people tend not to want to send overseas because if anything goes wrong it is more expensive. I just buy things, send them over to my friend, then they reimburse me for costs. Works out quite well if you have someone in the US who was willing to do that for you.