From time to time, someone is looking for a source of High Ratio shortening and I've listed sources here many times, as well as on the oldBC.
Sweet Celebrations was a great source for many years but they went out of business several years ago. Here is a copy/paste from a prior post:
Reply by swirth on January 26, 2012 at 6:22 pm
Emulsified shortening is also known as cake, icing or high ratio shortening. It can absorb more sugar and liquid than regular vegetable shortening and gives a finer/smoother texture to cakes while helping to keep them moist, as well as keeping icings more stable. It's mostly used in icings and cakes where the recipe contains a large percentage of sugar. Alpine Hi-Ratio Shortening and Sweetex are the most common brands.
There really is no substitute for it but you can buy it here:
and if you live near a Wilton store, I think you can get it there.