I started collecting comic art back in 1997 with my first piece, a Todd McFarlane Hulk page, while I was still in college. After that I didn't really get anything for a couple of years and only inched in a little with a Whilce Portacio piece around 1999. But soon after I was employed and the art started trickling in when a really cool piece appeared.
In general I try to get a single good example from each artist I like and that inspire me, although with a few of my favorites that's grown to include multiple pieces by guys like Todd McFarlane, Rob Liefeld, and Whilce Portacio.