Hey Mark,
I've seen them, but haven't tried them. I use Fruitawood and Maine Grilling Woods, and have been very happy with them. A 20# box from the charcoal store will last forever, since most of us don't use more than 6 oz ever!
I ordered a 10# sampler from Fruitawood a year ago (cherry, peach, apple) and still have a bunch left! So, be careful about ordering too much at one time; if it's a wood you don't like, you'll never get rid of it!