For beer, especially, the main distinction between basic German pilsners (I live in Berlin) was the social class that they're marketed to. Price is a pretty poor predictor of quality or taste, but you can choose to spend anywhere from about 50 cents to €1.20 to get almost indistinguishable beers. That doesn't mean to say that some aren't better than others, but that price isn't a good predictor of where they fit on the quality scale. (With craft beers things are pretty different, however.) There are very obviously working class beers, professional beers, etc.
With wine, my impression that almost everything that was sold at a grocery store broadly fit into the category of generic cheap wine. There is a weak correlation between quality and price, but if you sampled a bunch of them, it wasn't hard to find bottles at €3 that were better than the average bottle at €6, and bottles at €6 that were as good as the average bottle at €12. (They don't get much more expensive than €12 in grocery stores here. Note, wine is about twice as expensive for the same quality in the US, in my experience.) Notably, none of those wines would be truly interesting, just better expressions of their archetype.
The most interesting way to taste wine that I've found is at high-end restaurants that do pairings. Having a professional that just picks out interesting wines that they think fit with particularly quirky dishes has yielded more interesting results for me than the handful of wine tastings I've done. They'll bring out stuff that's truly weird and interesting if you're used to grocery store wine. And here at least, once you've, ahm, stomached, what you're paying for the meal, the glasses of wine aren't exorbitant -- about €8/glass, even at a place with a couple Michelin stars.
Relative to the other categories of booze, the place where I have genuine expertise is whisky. I have a large collection that's, well, worth more than my car. The beautiful thing about whisky, however, is that you can keep bottles of different things open for years and compare them to each other. That makes it pretty easy to figure out where you get the best bang for your buck. Over about €35/bottle, there's not a particularly strong correlation between quality and price. There are even some fantastic whiskies below that that punch way above their price-class (e.g. Laphroiag Quarter Cask, or Rittenhouse Rye). While there are some particularly unique and great expensive whiskies, even for a trained tongue and nose, it's absolutely no guarantee that a €100 bottle will be better than a good €40 bottle. Often it will just be rarer, and stroke the whisky-nerd ego to a greater extent. ;-)