I also buy my Accu Chek Mobile cassettes from "that well known site" I also have a Codefree meter with cheap strips, but there are too many problems with dodgy strips and inconsistent readings and the AC Mobile is the most convenient meter all round.
I have been buying the AC cassettes for 3 years from many different sellers and have never had one with a prescription label on it. There is a huge difference to me between £29 and £13 for 50 strips, and without them I would have to discard my favourite trusty meter and resort permanently to the inconvenient and not always reliable Codefree or Tee2. I am just as much a diabetic as those lucky enough to have strips prescribed, and as I can't have any prescribed then I will buy them where I can. I refuse to be made to feel guilty about this. (I am already saving the NHS money by using my self-funded meter to control my diabetes without recourse to any drugs and hopefully no complications)