The two products that have the highest concentration of Vitamin C Ester are:
Perricone MD Vitamin C Ester Eye Serum, $50
Perricone MD Concentrated Restorative Treatment, $100
It' is important to note that Dr. Perricone uses Vitamin C Ester in his products versus Ester C which is an entirely different ingredient.
Vitamin C Ester, also known as ascorbyl palmitate is a fat soluble form of Vitamins C when most are water soluble and go in and out the body rather quickly. The fat soluble form penetrates the skin cells and provides a higher level of benefit of antioxidant protection and promotes more collagen synthesis.
Ester C, also known as Calcium Ascorbate is pH neutral form of Vitamin C that is easier more gentle on the skin but is NOT fat soluble.
Hope this helps. Best. J