I do not live in the Indianapolis area, so I can't tell you about specific stores, but I would recommend looking for a local health food store or co-op. Local stores tend to be a bit more accommodating than commercial stores like whole foods, and usually if you are interesting in buying in bulk by the case or what-not they will often give you a discount. I would definitely try there first. There is a great on line resource for people like you who have gluten and other food allergies. It is called Living Without magazine, I met one of the editors several years ago and they are absolutely dedicated to your type of lifestyle. This is the website:
http://www.livingwithout.com/
Hope this helps a little.