That's a brilliant idea. Most of the research on BCAA has indeed used leucine.
Now, pure leucine isn't necessarily cheaper than a powder with a 2:1:1 ratio of leucine, isoleucine and valine. In my shop, a generic pound of the former costs more than a fancy box of the latter. But your mileage might vary...
Nope, never. I got twice royally screwed tax-wise ordering vintage t-shirts and electronics from the US, so I'm not too eager to try it with supps. I'm a poor student.
That said, Biotest products' are available through other channels for scandinavia (www.gymgrossisten.se). They have the whole catalog besides the "star" products (i.e: Metabolic Drive and Flameout).