I've mentioned in other posts that I really like Country Boy White Lightning oak pellets
. If you can find a local vendor, they are really good. They're sold more often as fuel for pellet stoves, but I have contacted both my distributor and the actual company on separate occasions and have been assured multiple times that they are food safe.
I get mine in Wisconsin for $5/40lb bag, and one bag will easily get me 24 hours of cooking. Flavor is not quite as strong as say a good hickory pellet (cookingpellets.com makes a fantastic 3 wood pellet, but shipping costs are kind of high). But it is still a good flavor. As far as heat output, if I need to I can crank it up to 600º or slightly over with the oak pellets.
These are now my go-to pellets simply because of cost and the fact that I like the flavor.
Congrats on your CS680. I have one myself, and I cannot express how much I love cooking on it.