They sell these at my local Academy Sports & Outdoors. I've seen some decent review on them, but haven't tried them yet. You may have to re-split to fit your smoker box.
The main problem with wood you find at hardware stores, WalMart, etc., is moisture content. Most of that wood has been out and exposed to air for quite awhile. What that means is that it's sometimes way too dry to use in a smoker; it burns instead of smoulder. Some of the wood suppliers, like Fruitawood or Maine Grilling Woods, control the moisture content really well, and the wood you receive it very fresh. Nothing worse than a flare-up of really dry wood in the smoker! Instead of thin, blue smoke, you see really heavy white/gray smoke that definitely doesn't smell as good. Not good for the meat.