Have to agree with the above post. I have a small 5 gallon wood bbl and the surface to beer ratio is way, way to high. I can'ty even imagine how much higher a 5L bbl would be - way, way too high. You are better off using cubes or staves. Trust me, you will only be able to age it in the bbl for about 1 week, 2 weeks tops before the wood overpowers the beer.
I spend about 200 bucks on mine and never use it any more. That said, if you want to try it I got mine from here .... edit: I can;t find where I got mine from but did a google search. I did and there are several.