I found (with TMs help) that I had caused my issue by putting a Buy Now (and forgetting to add a Start Price) and then went live with the listing. Once the listing is live you can not change or add anything to the price boxes via the edit system. I had to withdraw the listings and start again. WHY on earth can't one just go to edit and add what's required without having to start the process all over again. Its a very strange system. 

Thanks for the reply. I have done exactly as you described but to no avail. It's still greyed out. Cheers