I live in the U.S. and back when I was younger (7-12 years old) I was able to get ahold of Lone Wolf 1, 2, 3, and 4 and Grey Star 2 at my local library. Then I was able to read Lone Wolf 6-14 once I started 7th grade. They had them at the junior high I went to.
But yeah, they are hard to find...