Again, many thanks for this!
Since you seem to be so good at this, any chance you might be able to cobble one together for the
WHSmith ebook store? I've found that even after currency conversion fees, they seem to have some of the best prices on epubs. Someone else has already made a search plugin for the regular WHSmith site, but the ebookstore seems to be handled as a separate entity. Thanks again even if you can't do it.