Cheap way to source whole wheat flour for bread?

I recently purchased a bread machine and am after doing some math, it seems like baking loaves of bread from scratch can save quite a bit of money. I purchased a bag of whole wheat flour from Ralph’s recently and all they carried was Bob’s Red Mill which was a little over $6, which is a little bit more than standard bread flour (also could only find Bob’s Red Mill at this particular grocery store). I do live near a Sprouts that has bulk bins and haven’t checked it out just yet because I tend to lack self-control when I shop there and end up impulse buying foods/products I don’t usually use. Thanks!