Top Five Books
http://www.top-five-books.com/ (scroll down for the classics) has a small line of classics that I particularly like. The Sherlock Holmes books, for example, have the illustrations by Sidney Paget from the original Strand serials.
Right now, you can get "Pride and Prejudice" by Jane Austen with 36 full-color illustrations and other extras for free at Amazon, iTunes, and Google.
http://www.top-five-books.com/books-...prejudice.html
(click on the little store icons for links to the books at each store)
Pricing on the other titles varies between stores. The Top Five website lists all of the classics for $0.99, but Amazon has at least one of them for $2.99. You may want to check your favorite store to see if any of the others are free.
Many of these titles are probably available elsewhere for free, but I think these are nice, well-edited, illustrated versions that might be worth paying for.