Buying a barrel is certainly an option. I'd recommend going with the 1 or 5gal options. If you age white lightning in a barrel its basically whisky. A good beer to age in one would be a stout or a winter warmer, maybe even a scotch ale or old ale. Though what's a much cheaper option is buying oak chips, sold at most homebrew shops, and them soaking the chips in whisky then putting them in the fermenter to let the beer age on the chips. You can also buy different grades of toasted chips... Ex: dark toast or light toast. If you don't have a brew shop near you online vendors like Austin Homebrew should have them. FWIW your not limited to oak either. I've made an IPA aged on Spanish cedar from cigar boxes.
Because there is more surface area of oak touching the beer when using chips, it will imparts its character on the beer much faster.