Depending on content (how many panels, how detailed the backgrounds are, how complex the lighting is, etc., etc.), I range anywhere between 3-8 hours per page when drawing Grassblades. I do spread it out, though; I write/storyboard a whole chapter, then sketch all of the pages, and then I ink the first 6-8 pages before I start colouring. Then I switch between colouring and inking.
But generally, 3-8 hours per page. Sometimes more, if I'm drawing unfamiliar characters+complicated backgrounds and colour-schemes.
Colour obviously takes more time than greyscale - I once did a 7-page greyscaled comic from storyboard to finished grey tones in about three days of work, and that included several edits of the dialogue.