Amazon offers 4 lbs. of Optimum Nutrition 100% Casein Protein
in French Vanilla for $35.72
with free shipping
. That's $17.86 / jar and the lowest total price we could find for 4 lbs. of French Vanilla by $13, although we saw it for $8 less in December.
Note that it's listed as temporarily out of stock, but still orderable at this price.