I know several good mangas. I'll list some:
-Dragon Ball
-Dragon Ball Z
-Naruto
-One Piece
-InuYasha
-Ouran High School Host Club
-Full Moon wo Sagashite
-Gentleman's Alliance Cross
-Fullmetal Alchemist
-Tsubasa Resevoir Chronicles
-xxxHolic
-Chobits
-Azumanga Daioh
-Black Butler
-Fruits Basket
-Itsuwaribito
There are many more. These are just the ones off the top of my head. I hope these help.
As for where to purchase said books, I recommend Borders or Barnes & Noble. Or you could use the Internet. Sometimes they're cheaper there.