[joshd]

But he doesn't know even what conversion rates he could achieve because he chose to totally ignore non-US billing addresses. He's just assumed that it's not worth his effort.

He's talking about a web-based product. There is no reason to require a properly formatted address. When people are trying to give you money you should make things as simple as you can.

[tghw]

Not to be rude, but I think you're having a bit of a reading comprehension problem. Nowhere did I say to block non-US users, as you've repeatedly asserted I did.

What I am saying is don't worry too much about getting it right, especially if you plan on targeting US-based users first. If people have to pick a random state because the validation library you used always validates states, but only 5% of your users hit that problem, big deal. You should have a decent analytics package installed, and if you do you'll know what the bounce rates are for your international users, so you can decide if and when there is a business case for doing full i18n and l10n.