- There is a version of Traffic Travis that is free (haven't used it in awhile though, and you'll see why further down the list): http://traffictravis.com
You can even export white label rank reports from it!
- Allow me one more SEO tool recommendation: although it's not a rank tracker per se, check out real time analytics service called Hit Sniffer: http://hitsniffer.com
I've been using it for almost two years now, and whatever it may not have in eye candy makes up in it's very robust reporting.
Personally, I think $99 /mnth is so overpriced it's delusional, and I suspect SEOmoz's churn rate tells a similar story.