It's just through November, but if you buy their sister product, FusionReactor (the Enterprise edition), you'll get a free copy of FusionDebug. For more, see:
You can learn more about FusionDebug from several blog entries I've done in the past (see the "related entries" area at the bottom of this entry), including one on why I don't think CF8 is a death knell for either FusionDebug or FusionReactor.
(So no, I don't think anyone should read this as a move of desperation on Intergral's part. Rather, it's natural that the release of CF8 will cause some to say, "well, I could wait for CF8", but then for many shops moving up to a new release isn't trivial. That's why I said above: this may be most compelling for those whose interest in CFML step debugging has been piqued, but they can't for some reason move to CF8, whether Enterprise, Standard, or Developer. And of course, there are times when even a developer edition doesn't help if you need to debug a central development or test server. See my past blog entries on pros and cons of debugging a shared server. There are also some differences between the two that may even keep some using FD on CF8. More on that in a future entry, perhaps.)