Did you Google "16 oz isobutane" ? Tons of listings. Ordering more than one, maybe two, will likely be a problem online due to shipping restrictions.
But you live in a big city, go to Google maps, for Kansas City. Search for camping and/or outdoor equipment. It will list all stores related in the greater KC area and tag them on the map. You have to be able to find one in your area.
Of course one slight problem for you locally might be there is no where to camp around KC so no one would carry it. I don't know, never been to KC, K, or KC M.