If the money isn't too much of a burden, Id probably get CDM also. I only had the 10 test version. I did the first 3 untimed, and used the timer for the rest. I think the simulation of CDM will help you with timing, and destroyer will help you with diversity of problems.
It couldn't hurt to have a college algebra textbook as well. I found that I was wanting help setting up complex probability problems, so that's where the textbook with tons of practice problems/solutions came in.
If you are just starting and feel like you have to choose between speed/accuracy just don't get frustrated with yourself. I'd say the most important thing is that you train yourself to know where to spend your time, so working on timing should not be put off until the end.
In your first 5 tests, you may run into problem after problem that boggs you down for 2-3 min. If you find that you get flustered when this happens, try to stay positive. At least now you will know how to set up 1 more type of problem, and it will be easy on the actual dat.