I think one good reason for going through a middle man here in the States has already been mentioned - customs fees. By using a local merchant, the merchant is the one who deals with all the currency fluctuations, customs fees, etc.

I do however, prefer dealing directly with the kiltmaker, especially local ones. All but one of my tailored kilts has been made by stateside kiltmakers. I have kilts from Kathy Lare, Alexis Malcolm, and Matt Newsome.