It takes about a cup of rolled oats to make a cup of oat flour. This quantity of oats from Costco costs $.10. This is actually more affordable than any other flour I’ve used to make pancakes. A cup of pre-packaged Bob’s Red Mill oat flour costs about $.76 per cup. While it’s much more frugal to grind your own oat flour, you may want to grab a bag of already ground flour to save time in the morning when you’re making these oat flour pancakes.