We recommend reading also our blog post about app localization & translation here. It gives you an idea what to expect and how to think about localization and translation.
First you need to think about your target market. Is your app free or paid and whether there is some legal reasons to ignore certain markets. There's huge and small markets and also rich and poor ones. You should not overlook the poor markets as they can be a gold mine for apps looking the "next billion" users.
As a localization provider, I would love to promise this. But no. It's not. Yet it's a way to make your application greater which means more love from users and maybe eventually also from Apple. Read also our blog post about how to think of localization as an investment.
It's absolute necessary also to localize your app name, description, keywords and screenshots. AppStore gives you an 100 characters to define keywords but what they don't tell you is that you actually get 200 characters worth of keywords with localization. How? Well the English keywords and application name are always searched with the users language. So let's say user is Swedish and searching your app, it will match with both English and Swedish keywords and name.
Screenshot localization can be a pain but to ease it up, check our plug-in for Photoshop..