Bob's Red Mill is the only oat flour you can buy around here. It's good, but usually $3 for a 22 ounce package. I can get a 48 ounce tube of oatmeal for $1.39 at Aldi or on sale at other stores. All you need to make your own oat flour is a food processor or blender. My cookbook told me that I could use a spice grinder. I bought one at a gourmet store-but I really didn't know what I was doing. The thing was tiny, and although it functioned properly, it took FOREVER to get a usable amount (that's what she said). So, go with the blender/food processor.
From Quaker's web site:
"Place one or more cups of Quick or Old Fashioned Oats into a food processor or blender. Process for 1 minute, or until the oats are the consistency of cornmeal or a course flour. Store unused (dry) oat flour in a covered container as you would wheat flour."
I used my food processor and my oat flour pancakes came out pretty well-a touch thick. I will try the blender next time and see if I can get the oat flour a bit finer. This is so easy to do, I am not likely to buy oat flour ever again.