Never, ever ever ever buy store bought horseradish cream sauce. It's so easy to make at home and it's light years better.
Horseradish cream sauce is pretty easy. It's sort of like how I make pesto - just a little bit of this a little of that and I mix it together and taste it.
If it needs a little more horseradish, I add it, etc. If you want a recipe, I would follow this:
1/4 Cup Fresh Horseradish (I buy the kind that's refrigerated)
1 Cup Sour Cream
2 Tbs of Cream or Milk
1 Tbs of White Vinegar
1/2 Tsp Sea or Kosher Salt
1/4 Tsp White Pepper
Just play around and customize to suit your tastes. Stay hungry!