I have made my own chips from native white oak. I've done chips, sawdust, cubes and strips. WARNING- Do NOT put it in the microwave. I did that with a strip of oak 1/2 x 1/2 x 12" and 30 seconds of microwaving filled the house with smoke- another few seconds and the fire would have erupted. I put the wood of choice on a cookie sheet in the regular oven at 400 for about 60 minutes. It doesn't come out as dark as some I've bought, but I get chicken since the microwave episode(the house smelled great for about a week after that episode).
Best results so far have been the strips- roast for an hour and then placing on the electric stovetop burner (set on medium high) for a few seconds and then turn a quater turn. Go around a few times until it gets a charred color. Cool and it's ready. I've used the oak in quite a few batches and they seem to give the desired results.