I have ordered from them in the past and was very happy with their products. But I would like to buy about a 20 pound bag of Cake Flour, a 5 or 10 pound container of Shortening, About 10 pound bags of Sugar etc.
Let your fingers do the walking and look in the yellow pages for bakery supplies. It is hard to beat the price of Costco or Sams Club. We have one in San Diego that is called Lakeside Poultry but has a huge assortment of flours, sugars, shortning, hundreds of items that would be used in a commerical bakery and will sell retail as well as wholesale. Call one of your Bake shops for the names of suppliers. Ordering on line will double the cost of your items with shipping.
The big problem is that the quanties you are looking for are just "quantity" purchases and not "bulk" packaging. For example - a bulk bag of flour or sugar is going to be 50-pounds! Here is one source: Honeyville Grain, Inc. where you can get a 50# bag of cake flour and a 50# bag of sugar (shipping included) for $89. I do like their flat $4.49 per order shipping cost.
You might want to spend a little time Googeling the items you are looking for, but put the word BULK at the beginning, like "bulk cake flour", "bulk cake icing", etc.
When it comes to things like shortening - I would buy only the quantity that you will use with 3-6 months - the stuff can go rancid which can result in having to either throw out rotten tasting product or tossing unused shortening. Commercial/wholesale suppliers like Bunge Foods make several "shortening blends" that are geared to specific things, like baking. They are usually sold in about 35# boxes. You'll just need to find a distributor.
The problem with "buying in bulk" from a 50# barrel at some place like GNC, or my favorite food store Central Market, they are not always cheaper per pound than buying a bag off the shelf.
As others have suggested - break out the phone book and do a little research for local suppliers of bulk/wholesale food items. Or, join a Sam's Club/Costo and buy in smaller quanties.