In 2009 we visited the Musee des Bieres Belges, in Lustin. Very interesting musty little place, with a great set of taps. They had a lot of older bottles for sale, with stupid cheap prices. They worked off of a price chart, volume vs. ABV . It didn't matter what the beer or brewery was, or the age, just look up the price. I snagged a 1998 bottle of Rodenbach Alexander for 2 euros. We got happily loaded while we were there (had a bus to drive us home).