I'm on the verge of pulling the trigger on something like that myself.
Bissell's Proheat 2x have gotten very good reviews from what I've gathered during my research. Most notably because they heat the already hot tap water to at least twice the temperature. Many who have used them say that feature when combined with the rotating brushes leave their carpet's as good if not cleaner than when the have the pro come in.
MorBiD