I've seen them in liquor stores next to the high-end whiskey. It's a "do it yourself" bourbon/whiskey kit. Small new oak barrel, which they suggest filling with vodka, then drain and "enjoy". Is this what you were talking about or am I way off?
If you're unable to find the barrel, you can always soak a couple of oak cubes in your favorite spirit. Would be much cheaper than having to get a small barrel every time. Pretty easy to do and produces great results.