As for the "how much space do you need to do P90X questions... Here is what I know I need (been doing P90X and P90X Plus for almost 2 years now)...
1. I need the ceiling to be at least 9 feet high.. (Mine is 9ft and I scrape that on some of the more explosive jumps that you can get into). I am 5'10, so it's not like I am very tall. I also don't feel I am all that "athletic".
2. You need enough floor space that you can jump forward, backwards and side to side. You also need to be able to turn in a complete circle while in a prone (starting pushup position). You get to do some rolling around on some of the exercises - it takes a little more space then you "think" because as you get better at the exercises, you tend to go faster and move further on them. This includes things like side jumps, lunges (with and without weights), forward, back, side kicks and simply jumping as far as you can forward, spinning round and jumping again.
As for the cost of the DVD's.. Folks, when it comes to exercise (been hitting a gym lifting weights, etc.. since 1978 or so) this is the best $150 that I have ever spent on the exercise front. It's well worth the cost of entry.
If you want more details about the program, just PM me questions and I'll answer with how I use or what I see from doing the programs.
2007 3.0si Roadster Black/Red, sport, Piano Black F14 Forgestar's