Home depot has the large bags of hickory and mesquite chunks and maybe some others (?) You will have to find a more specialized store to find cherry, pecan, oak and the like. Try these big grill stores... I think the Academy Sports in Auburn has a good selection. Avoid red oak as it can develop a fungus that will make the meat taste awful.
I would love a reference to someone who would deliver maybe a half/cord of slit Hickory or pecan to replace the crappy Kingsford charcoal on the market today.