I am not the voice of reason at the current moment. I, too, took advantage of the CIA sale and am getting quite a few items off of the VF trade forum or the YaYa's swapmeet. I tell myself I am allowed since I am not paying full price.
Do I have enough videos? More than enough! Do I want more? You betcha! I like having a selection to fit both my mood and my desired intensity level. For example, I am currently under the weather (bad cold) and Cathe is way too intense for me. So I will do some of my lower intensity workouts (if my body is up for it) until I recover and then go back to Cathe and others.
Workouts are on my Christmas wish list and I'll be getting a bonus at work next month and a chunk of that will go to a massive DVD purchase as I transition from VHS to DVD. But I am finding that I am more choosy with what I will spend money on. When I was starting out I would buy so much without much thought. But as my collection has grown, I have found I am a much more patient and informed consumer.
My motto, variety is the spice of life. Since videos are my primary source of exercise (no gym dues, no big pieces of equipment), I will indulge myself from time to time to vary my collection. It just so happens right now is one of those collection expansion times.