Have you tried this store?
Sasuga Book, not a huge choice, but being in USA it is faster. Sometimes unfortunately they are out of stock so they order from Japan and that takes a bit longer (but no extra charges and regular shipping sometimes is free).
As per kids books I had bought one which is bilingual called まんが日本昔ばなし。。。妖しのお話. But I soon realized that strangely it is easier a "grown up" book. I guess that is because a kid book is not really written with the Japanese we study, but more a childish one? Don't know, but truth is I temporally abandoned it and I am reading something I like better (紫蘭の花嫁, むらさきらん の はなよめ).