creating WordPress sites from scratch can be a pain. WP sites are built largely from what they call 'template tags'. the template tags are a basically a bunch of PHP functions stored in other php files. I'd really love it if they were a different color while editing as there's often lots of straight php going on.
lots of the tags have there own set of conditions you can set. you can look them up on their wiki but oh man would assistive code complete be sweet!
I'm on my fourth wp build and am finally pretty comfortable with lots of the tags but there are about 1539 posts per day on their forums from people just starting to develop for it. I think wp currently boasts 1 million+ users. I think there is quite a market there. If there was a wp aware editor out there for $25-35, I'm sure it would get recommended regularly on the forums, maybe even on their home page.
of course, I'd be happy with just some wp syntax highlighting.
Will
ps. http://www.wordpress.org