I have been toying with this waves rennaisance bass plugin. It bassically has a resonant filter with a distortion. It has settings for small speakers, etc. expensive, though.
Unless you have a project in mind I wouldn't bother getting a maxxbass. You can do just about anything you need with your EQ. Don't forget it wasn't your mix that was the problem, it was my $5 speakers that sucked.
Seeing this thread again did cause me to revisit your link because I never did actually hear the vocals with the tune. Although way to busy for my taste, the vocals sit pretty well into the rough mix. In contrast, the final mix sounded like you added a wee bit too much reverb causing them to sound like they were recorded in a chamber. I definitely liked the rough mix better. What exactly did you do to change the dynamics between the two mixes?
Man, that track was so damn tight! I didn't give it a critical listen because I was too into the bass...that bass was fatter than Aunt Bessie on Thanksgiving day!! I love it. Bass rules the world!