Well it took a few tries but I finally got a delicious batch of sour cream. It was actually my husband who figured out what I was doing wrong when he said maybe it needs to be kept warm. It was so simple I had completely overlooked it and now I am feeling very silly. Anyway I now know exactly how to create the most wonderful sour cream and although it will not save me as much money as the yogurt it is definitely cheaper to make my own especially when we are talking organics.
1 cup heavy cream
1/4 cup buttermilk*
In a pint size mason jar pour in the cream and buttermilk, screw on the lid and shake to mix well. Place in a warm area away from direct sunlight (I used my oven with the light on overnight) for 12 hrs. After 24 hours when it seems to be slightly thick place in the fridge and cool completely. It will thicken up a bit more once it is cool.
*I have read that you can replace the buttermilk with either sour cream or mock buttermilk, 2 tsp white vinegar plus enough milk to make 1/4 cup let sit for 10 min before mixing in to the cream. If I get successful results from either of these methods I will be sure to update.