DOpus is overpriced. The problem is that no other program offers what it can do, so it's not like there's an alternative. I tried mashing together a suite to replace it using freeware or cheaper stuff, but it took too many programs to accomplish it and became a headache.
I also take advantage of the portable license so I can use it on multiple computers and retain my settings. You can save multiple profiles (layouts) per computer.
xyplorer is a good cheaper alternative. and 40hz turned me on to Q-Dir a few weeks ago, which is VERY interesting and handy (and free). If you're not committed to a file manager yet and are looking for free ones, start with Q-Dir.