I order online since I have only seen them at the 1500 a couple times and at a huge mark up. When shopping for them make sure you understand what thickness you are buying as some places are more expensive then others but it is due to thicker bags. They range from 3.5, 5, 7, and 8 mil from what I have seen for large gallon and 5 gallon storage.
There is an LDS cannery in Indy. Google it and see what their hours are. My friend goes every few months. You don't have to be a Morman to go but call them and ask when they are open.