yes, Tweeter, wikipedia and blogs are the most reliable source of information....not!
I'm not saying that P90X is a magic program. I'm just saying that to me, as a beginner, it's worth $80 to have everything at one place (and have at least some authority standing behind the program), rather than spend 200 hours reading 50 different blogs to figure out the same thing at the end.
I'm not taking working out too seriously like you do. For me, it's a fun thing to do, and I do it to stay healthy and improve my tennis game a bit.