Cost is an important thing. Quality is also important. Canned beans are expensive compared to cooking dry beans if you just price the ingredients. Labor is involved to cook the beans. Figure your cost of product plus cost of labor and compare costs.
Leftover beans are also an issue. Beans have serious cooling and reheating problems. Beans are mentioned at ever Food Safety class as an example of food that can go bad due to cooling or reheating too slow, and remaining at critical temperatures for too long.
If you have a commissary, and a way to heat and cool quickly, then home made beans are a good option. I have found that the beans that we make are much less cost than canned beans, and much higher in quality. We pride ourselves on our fine BBQ and the first time that customers walked away talking about how "awesome" the beans were---It kind of upset me. Most people today are used to getting the same ol' canned beans everywhere they go, so home made beans impress them.
One pound of beans equals 2 cups of beans
or 3 pounds or 6 cups of beans will make approx 50 four ounce servings
so for 100 servings use 6 pounds or 12 cups of beans.
I am a BBQ Caterer but I am also a Chuck Wagon Cook and a Dutch Oven Cook so I have been cooking all types of beans for many years. My own belief is that the word "can" and the word "beans" do not belong in the same sentence, but that is only my own humble opinion. Check your costs--include in your cost the fact that you may be throwing out beans due to lack of improper cooling or reheating facilities, or storage facilities. Canned beans are an option. Canned beans are easy to store and are not labor intensive.
I refuse to argue with any caterer that uses canned beans---they may have reasons why they use them. I will simply steal their customers.