VSL would certainly be my first guess. I see quite a bit come up for sale on our local auction site, as I live close to Belgium. This shape and colour looks like the sort of glass they made in the 50s - 70s. If it had had a more twisted look, I would have been almost certain.
But I can't make a really positive ID since I don't have any source material to back me up. It pays to keep looking though and searching for VSL, because much of their work was labeled, and you might just see a similar one with a label turn up on internet. Good luck!
And of course $6 is always a bargain for a large vase like that in good condition...
Astrid