I couldn't believe my taste buds the first time I had Duchess, Petrus Pale, Cuvee Rene, Rodenbach Grand Cru and ESPECIALLY Cuvee Des Jacobsins Rouge. I though they were all incredible and can be found in grocery stores. Today I don't care much for any of them, especially the Flanders Reds which are just too sweet, but they are all a great place to start. I've seen Duchess blow the minds of exclusive lager drinkers, wine drinkers or others who just don't do beer. I still love Orval though, which is also easy to find.
If you are interested in trading for some world class sours, I wouldn't look much farther than Supplication and Consecration. They're pretty readily available and just as good as a lot of the hyped up stuff.