There are a lot of websites that sell cans and buckets of 'storage food.' Don't for a minute believe they are all alike! Some have brick and mortar stores (usually in Utah or other areas with a large LDS presence), some don't. Some sell only pre-packaged, just-add-water meals in pouches or cans, some sell the basic ingredients for you to build your own meals. The prices vary significantly. The variance includes different prices for the exact same brand and size of item. What varies even more wildly are the shipping charges.
I performed some cost comparisons among three sites that I believe to be reputable (based on having ordered and received good quality edible food from each). When comparing like items, the one with the least expensive cost for the items had the most expensive shipping. Ultimately, it was about twice the total cost of the items if purchased from either of the other two websites.
When I buy from websites, I stick with the ones that have low fixed shipping costs and occasionally rerun my comparison to make sure that competition has not changed the equations -- or their answers! For some specialty items, like canned butter or green coffee, I will venture out, but it is rare. As an aside, if you are adventuresome and want to can your own butter, the website paratusfamilia.blogspot.com has some great posts on home canning of butter, bacon, cheese and other such items.
I also usually buy primarily from the 'sale items' for that month and keep my purchase at $100 or less, including the shipping, for each purchase. If your budget can allow for more, then the low-cost shipping sites like beprepared.com and honeyvillegrain.com will stretch your dollar even farther.
For items like sugar, baking soda, salt, and a few other dry commodities that I can easily rotate in my daily cooking, I do not buy in the expensive #10 cans. I have some used bakery buckets and several BUDDEEZ containers that I use to store and keep these items dry. I buy the BUDDEEZ at Ross Dress for Less in the household/kitchen area. They are not expensive and are made in America, which is a plus. (to see what these look like, go to buddeez.com) I have even found 25 lb sacks of wheat at Wal-Mart on rare occasion, and the price was right! I threw it in a bucket, added a top and started using it. Best shipping rate yet!