I did a quick search on /r/AsianBeauty and found that a few people recommend either ebay or a couple of different online sellers, such as this one: http://www.adambeauty.com/showitem.php?catid=10508 That's a link to their sunscreen section. I've never bought anything from there, but when my current sunscreen runs out I'm planning on trying Japanese sunscreen too. The prices seem pretty good, shipping is $2US, and they take paypal.

Also, have a look at the Asian skincare buying guide from the sidebar: http://www.reddit.com/r/AusSkincare/comments/2eihtx/asian_skincare_shopping_guide/ (sadly, I'm in Tasmania and haven't found anywhere local yet, so I'll be buying online)

I don't know about Asia in general, but Japanese standards are definitely high. A couple of threads talking about Japanese standards: http://www.reddit.com/r/AsianBeauty/comments/2vbqqa/are_asian_sunscreens_regulated/ http://www.reddit.com/r/AsianBeauty/comments/354en1/how_are_asian_sunscreens_to_thin_and_cosmetically/

The reason people say that about the white cast is based on physical sunscreen. If you're using a physical sunscreen and there's no white cast (and it's not tinted...maybe you could try tinted?) it means you haven't applied enough. With a chemical sunscreen, there is no white cast no matter how much you use, so you do need to make sure you're applying enough. With any sunscreen, I like to apply in 2 thin layers to get more even coverage...there's nothing worse than accidentally missing a patch and then going in the sun all day!

Lastly, you could try going in to a store like Priceline where they have staff on the floor to help (usually hanging around the beauty section). If you go in and ask specifically for a face sunscreen that doesn't leave a white cast, they should be able to help you out, possibly even with testers so you can check on the back of your hand.