Migrating from Drupal to WordPress is one of the more difficult migration paths. There are scripts available to migrate from Drupal 6 to WordPress but the way in which those scripts were created only allow for the migration of a specific version of Drupal to a specific version of WordPress. Most of the time, these scripts are written and shared by people that couldn’t find an easy path to move from one to the other and generally give up on maintaining the script after completing their move. Instead of relying on outdated scripts, you may want to check out MigrateToWP.com. These folks specialize in moving sites from Drupal into WordPress. While that is their specialty, they’ll also move plain HTML, Joomla, Blogger and other CMS sites as well.
Judging by their pricing page, they seem rather reasonable for what you get, especially when you compare those prices to getting a developer to provide you with a custom migration script. What’s not offered through the Professional plan can be accomplished with plugins after the move is complete. If no predetermined planned suits your needs, you can get in touch with them and they will provide you a free estimate.
If you’ve used this service before feel free to share your experience.