I bought a bag target 2 yrs ago. Liked it for being nice and heavy (30lbs or more) and dense.
have shot its thousands of times between me, my wife, and buddy of mine.
picked it up at bass pro for $49.
http://cf.mp-cdn.net/9f/0b/343c52d1f...45f75348b3.jpg
don't know whats in the center of it, but its some good stuff.