I think it’s any wine that’s a combination of old, rare, hard to find, expensive, and/or that the wine geek is making an effort to share something special to her or him. I think that it’s baller-esque when a college student that usually drinks $9 bottles brings a $35 bottle to a tasting group. It’s someone that’s clearly trying to be generous…and I think that happens all the time in the wine community.
The term is almost always used here to refer to mega tastings, usually 10+ epic wines in one dinner. I’ve rarely seen it used in reference to a single bottle.
Anyone who uses the term baller non-ironically is an asshole. It is slightly more acceptable to use the term ironically, as when someone tells you he bought a Muscadet by the case.