where can i buy genus erica winter flowring

Vincent, the genus/species is the basic wild plant. Botanists and Nurserymen then either select very good forms of the wild plant or deliberatly cross breed them to produce the 'more common' named varieties found in the Garden Centres. Sometimes the named varieties are an improvement on the wild plant and sometimes they are an abomination. Beauty is in the eye of the beholder. Some of us prefer one sort and some the other. If we all liked the same thing life would be very boring!
In the case of the heathers I think that the nursery plants are much more garden worthy than the wild species. I don't know that there is a winter flowering 'wild' heather but there are certainly nursery heathers that will flower at this time.

I have Erica carnea 'Springwood White' in my garden, Vincent. It is Winter flowerer and is still flowering. It is generally regarded as one of the best and there is a picture of it in the plants section of my homepage.
Bernard