An experienced artist charges anywhere from $100 to $250 per page (I would say $200 is standard though), and that's only if they're making inks/pencils/colors/type alone. Their prices go up the more you want them to make (obviously).
I charge $100 per page and I usually just stick to inks and pencils and leave the coloring and typesetting to someone else (who gets paid a separate fee) just because I am not that comfortable with those two areas yet. Also, I live in NYC, so ya know, everything is a bit more expensive here. I have taken jobs for $50 a page when I'm desperate, but $100 is my usual rate.
Hopefully that gives you a nice base on what to expect!
EDIT: Obviously, more experienced artists can charge way more! I know of people (won't say names because privacy) who charge $500 per page because of the reputation they have. I seldom ever hear of people getting paid hourly when they illustrate comics, and with enough reason. This is not a job where you clock-in, so there's really no way of knowing. Most artists just have flat rates per page.