Hey there,
I'm nearly at the end of my PPL and have been using the CRP-5 for all my nav work. Like has been said it is the wheel for the commercial exams and so it pays to get used to using it now. Also a point to note, make sure that you learn the proper way to use it during PPL. For example when using the wind side you can use two different methods, one is used in commercial exams (wind down) and the other is supposedly easier to use and used for PPL but is however not used in the ATPLs.
As for headsets I decided that I would rather pay slightly more for a better headset and so when I was over in the US I picked up a pair of bose-x for £400 odd. Great headset, really light and the ANR is really impressive. I'm training full time so fly as much as I can, plus will obviously be hour building. I'd rather spend a little more and make sure I don't loose my hearing hehe (I already have a slight bit of tinnitus, too many gigs whilst at uni, don't wanna make that worse!)
Good luck on your PPL