What good free text editors do you recommend on Mac that have similar features, like syntax highlighting, auto-indent, and regular expression support?
You can make new accounts, but I would suggest getting your current accounts unbanned. A short mail to pg(you can guess the email address) on the lines of "I believe my hn handle http://news.ycombinator.com/user?id=mark_up is wrongfully banned" does the trick.
Any Cocoa/OSX specific GUI editor will suffer from being less powerful, less well tested and less portable (whereas vim/emacs are available on any imaginable platform, allowing you to keep your editing muscle memory).
The end result is that you either fork over the money (not entirely unreasonable for a tool you use so often) or learn to work the excellent free editors that exist.
Another in development is Kod ( http://kodapp.com/ ) that I've not used much yet. My daily editor now though is Sublime Text 2 (free to try out).
It is probably a bit friendlier, out of the box, than vanilla Emacs, at least from an OS X perspective.
text wrangler: http://www.barebones.com/products/textwrangler/download.html
redcar: http://redcareditor.com/
but you're really not gonna get any better than textmate or sublime text 2