Yandra have you tried cpareviewforfree.com? The questions are pretty good and a good change up from other test prep software. It's completely free and very accessible. I use it practically all day at work to study a question here or two from there when I'm just waiting for crap to post or load or if I'm sign off approvals and stuff. Just think about how much time people waste on a forum or checking e-mail at work and put that into that site and you'll probably get a ton done that way. I usually get about 20-40 questions done from that site a day just from getting questions here and there plus lunch break. I take my time understanding his answers and his explainations are very good. I just e-mail him if the explaination doesn't make sense and he is pretty quick to respond. The highest % of correct answers I've ever gotten using his mini-exams was 85%. The questions are pretty tough IMO.
I jumped 9 points on my REG section using them and passed BEC my first time thanks to their explainations on the cost accounting and CAPM model.
For formulas. Knowing that any formula that says over or to means a division formula e.g. debt to equity = debt/equity helps a bunch.
REG - 67, 76 (Q4 2009) - Used CPAExcel first time, Used CPAExcel + CPAReviewForFree
BEC - 83 (Q1 2010) - CPAExcel + CPAReviewForFree
AUD - 89 (Q2 2010) - CPAExcel + CPAReviewForFree
FAR - 81 (Q4 2010) - Roger CPA + CPAReviwForFree