Need some advice for second-hand manga

Hello, guys >O<

I'm at a loss right now and maybe some of you can help me out with an advice. >__<"
In my country a lot of Manga are out of print really fast (and therefor really expensive up to $200 for one book) thats one of the reasons I started to get them in englisch from the US or Canada. That worked pretty well so far, but one series is giving me a bit of trouble. (Out of print as well, yeah :D")

I was wondering if some of you have tips for websites/proxys or something that could help me find them? I don't really know how the second-hand market works in the US/Canada. (If you have specific sites to check?)

I would really appreciate the help! T^T

You only want physical books, not digital?

I'm solely an English speaker, but apart from ebay I look at betterworldbooks, thriftbooks and abebooks.

 

The first two sell second hand books, the latter is a marketplace for booksellers around the world.

Abebooks has the most variety as it is a marketplace, but check the shipping prices because sometimes they're pretty silly.  I live in Australia though, I don't know how that compares to Germany.