As a powerseller in eBay and also as someone who is single handed and disabled I have some perspective on this matter. I am located in the UK but 90% of my buyers are in the USA and my store is on .com. Bearing in mind that I only post twice weekly and have to pay someone to do post office runs as I dont drive I manage my buyers expectations. I tell them air shipping to the USA is 7-10 working days ie 2 weeks whereas most items actually arrive in one week. So if they miss my mailing by a few hours and the package does not go out til a few days later they are still pleasantly surprised by how quickly it gets there. I also keep my buyers well informed by sending them a "payment acknowledgement" when they pay and a "shipping advice" when the item is sent. So far only one or two nuts have complained about slow shipping, and they did not realise it was coming international.
You have to learn to "manage" your buyers and use a bit of psychology on them.