Here's a little from my experience:
Passed AUD using only CPAReviewForFree.com without spending a single penny. I just did the questions all the way through about 7 times, lol. Although I thought that was pretty cool, I only got a 79. Knowing that other sections (REG/FAR) would be more difficult for me, I was worried that the free stuff wasn't going to be enough. So I grabbed the Wiley Test bank from Jeff.
Used the Wiley & CPAReviewForFree for BEC and passed with an 88 – much more comfortable with that score. Never needed any lectures or anything… which speaks well for Wiley since I'm several years out of college and not the sharpest tool in the box. I highly recommend Wiley for that reason.
That said, though, I feel like I might need a little extra umph with REG, so I grabbed the Gleim system. The lectures are horribly boring, but the Audio helps for my commute, and I like all the additional MCQs in their test bank. The SIMS are good practice, too, I suppose/
LONG story short… anything's possible, but you'll have to feel it out for youself. Honestly if I had the money (and no kids/no mortgage/etc…), I would have gone with the full course from Roger or something. The key is to not underestimate this exam. Neither should we understimate the future benefits of passing it, which as many have said, will far outweigh whatever costs we put into it.
AUD - 79
BEC - 88
REG - 87
FAR - 86 - Woot, all done!
Ethics - 100