@plainoldme,
This may be coming a bit late, but there a lot of graphic novels that might spark your students interest. Comic book stores will stock some, as do a lot of used bookstores (I have no idea where you are located, but
Half Price Books in the Southwestern US usually has some sort of inventory onhand.) Of course, there are a lot available online, as well.
I grew up a comic book geek, and kept up with it longer than perhaps I should have. I only stopped collecting in the 90s when the paper shortage resulted in some dramatic price hikes. But a couple of years ago, when I quit smoking and suddenly had more cash than I was used to, I went on a little nostalgia trip and started visiting my local comic shop for a while. They still have a lot of "classic" graphic novels as well as collections of your standard superhero and fantasy fare. Here are a few suggestions, in no particular order:
Collections of
Hepcats by Martin Wagner
Jar of Fools by Jason Lutes
Sandman by Neil Gaiman
Cerebus by Dave Sim (The "phonebook" collections of this 30-yr running series can be read as stand alone stories. Much of the series is amazing, although the last few years of its run were absolute crap. One section,
Jaka's Story, is a fine representative of the graphic novel.)
Maus by Art Spiegelman (sometimes controversial)
Collections of
Strangers in Paradise by Terry Moore
A Contract With God and
A Life Force both by Will Eisner (anything by Eisner will work though.)
Bone by Jeff Smith
Collections of the
Bacchus series by Eddie Campbell
And I know this might sound silly, especially if you are looking for books with longer plots, but there are also plenty of collections of comic strips that remain pretty sophisticated. I still miss "Calvin and Hobbes" by Bill Watterson.