I've been able to find a large variety of wood chunks at the local Home Depot, Lowes and Menards. Everything you can imagine except Oak for some reason.
Today I just went to the firewood dealer for fireplaces. I explained my delimma, and he let me go out to the Oak pile. I grabbed about 5 smaller pieces that had the bark removed. He charged $2.00. I got them home, pulled out the table saw and sliced them in approx 2 inch lengths. I ended up with around 15 lbs of great seasoned Oak. In the absence of other alternatives, the local firewood dealer might be an option.