Being in Canada, I am quite used to the ads that say "US only" but really cannot blame them. All the reasons stated above are valid, along with the unspoken one that the US is the largest market for these forums, so the US-only sellers really are not limiting themselves much. As int'l buyers, this means we miss out on some deals, but I've been on both sides of the fence and am at least glad that the destinations are listed in the ads! I really don't appreciate the ones with no destinations excluded, only to get a PM reply saying "I won't ship outside the USA."
Related to this, I recently put a 60-250 up for sale, but limited it to Canada-only for many of the same reasons as US-only sellers. Sold it quickly and without problems here in Canada, while a very similar one listed before mine, for sale as US-only, still hasn't sold! It's a marketplace, so you never can predict what is a "limit" or not.
BTW, I've sold and shipped things to Asia, Africa, and the deepest depths of New Zealand without problems. However, I used to live in Europe, so I already know to avoid the national post services there...
Last edited by panoguy; 05-02-2013 at 07:10 AM.