I read these comic books (and still own them) in single issue form. I believe they are available as trades, though I cannot find any on Amazon. Which is a shame, because I think every fan of fantasy should own copies.
Mouse Guard would appeal to any fans of Lord of the Rings and the Rats of Nimh. Not to mention the art in the books is breathtaking and detailed. I'm holding on to these books with plans to pass them onto my sons once they are old enough. These books are a classic and should be in the collect of every fan of fantasy. I have my fingers crossed for a reprinting of the trade paperbacks or possible a hardback edition.