Originally Posted by epic
Ditto on Strolz.
Yep. I wear a US 17 and mine fit great (you want the "Favorit" model; that's the one that goes to extreme sizes/widths.) Not cheap, but it works.
Surefoot also has some pretty big shells, although they cost just as much if not more. If you need/want custom footbeds as well, they might be worth considering. Although most shops that do high-end bootfitting can make those as well.
The shop I went to for my boots had a couple other (cheaper) shells that were in my size -- I think a Lange, and maybe a Daleboot? One didn't fit well around my ankle, and I liked the fit of the Strolz better than the other even with the price difference. But I'm not sure if either of those came any bigger than what I had on (32.5, I think.)
Big resorts often have rentals of very large boots, at least up to 32.5/33 or so. If you can find somewhere nearby that does, it might be an option if your friend doesn't want to drop $600+ without knowing whether he'll really like skiing.