Cro-Hook is a trade mark of Wrights, they are a double-ended crochet hook (Bates uses that clear/simple term) and Pony calls them Tunisian crochet hooks. When my mom taught me to crochet, she had a Cro-hook and I used it to make a scarf and hat set that I still own (now over 30 years later).
I too have been looking for either afghan or double-ended crochet hooks for some of my project ideas. Really, if you need an afghan hook, why not get the double-ended hook and just put a point protector on one end? I like it when a tool has two or more uses. Boye says they are carried at A. C. Moore, Michaels, JoAnn's, and Wal-Mart. That must be their general product line and not specific to the Cro-Hook.
I found this site (www.spinblessing.com/search.php?Query=Boye
) where you can order double-ended hooks in US sizes F through N. Really, if you need an afghan hook, why not get the double ened and use a point protector as your stop? I like it when a tool has two or more uses. Hm, a 14 inch, double-ended hook for the price of about three regular aluminum crochet hooks.
Good luck in your search.