ur so damn lucky
i only own 2 mangas and i read off the web because its too expensive
$7 - $10 is actually quite a bargain. They use to run $15 - $20 dollars for a tankoban and before that you only got 1 chapter issues for roughly $3 - $5.
There is a used bookstore in my town that sells them for $5 or less; it's mostly old and out of print titles that are kind of dirty but there are a few gems every once in a while.