--- $$$ is a huge factor for me.
It is for everyone, I assume! Even the lucky folks who can chuck hundreds of bucks a month into the hobby want best value for their coin.
One of the American resellers of Copplestone currently has a markup of nearly $10/pack over what Copplestone charges, given current exchange rates. Their S&H charges are roughly the same as Copplestone's. It's actually
cheaper to order from overseas rather than use this particular North American retailer.
Granted, this isn't always the case, but it's worth comparing prices and
checking exchange rates before assuming overseas ordering is always the more expensive option.
My earlier comment about Americans being the first to ask for American retailers wasn't intended to be insulting, just an observation of national stereotypes. If the discussion is on postal duties and the obnoxiousness of same, it'll be the Brits and Canucks again and again; requests for "does [company] have a distributor in [country]" are likewise nearly always Americans. Aussies and Kiwis always complain about the absurd S&H to ship stuff down to the underside of the world. And so on.

Oh, and while I'm posting away:
http://www.eurekaminusa.com/[/color]]http://www.eurekaminusa.com/