I think that I've mentioned Heaven and Earth designs before--they take fantasy art and turn it into fantastically detailed cross stitch designs. Among their comtemporary stuff, they have a bunch of the Pre-Raphaelites, which count as fantasy in my book.
My downfall is one of my favorite Pre-Raphaelite paintings, John William Waterhouse's Boreas. H&E has a chart for it. This chart is for a piece of needlework about 9 by 12 inches, call it 110 square inches for a round number. This isn't so bad; I've even done larger pieces. There are only two problems: for one, unlike a lot of patterns, this one has no empty space. Every square of the pattern has a symbol in it; the ground fabric doesn't show at all. Two...it's recommended that you use 25-count fabric. That's 625 stitches per square inch, for a grand total of 68,750--give or take.
Do I really want to devote that much time and effort to something I'll end up just hanging on my wall? I mean, I could just buy a poster or something.