There’s usually no substitute for age when looking for complexity, and wines that drink complex when young tend to have a distinctive profile that doesn’t appeal to all.
With that caveat, 2 wineries whose offerings (both the reds and whites) show lots of complexity on release are Musar and Lopez de Heredia. Both can still be found for $50 if you look.
Ridge wines can get quite complex, but like others have said, I think these needs time to let all that upfront fruit morph.
As a category, the Loire and Chianti offer many wines that gives a good range of flavors and nuance. And gewurztraminer is usually a very expressive, multifaceted grape, but it can lack subtlety.
Not surprising. Some people need to do more research before they post. I found a whole bunch from just one local store. https://bassins.com/search_results.php
I don’t agree. Some of the common grape varieties known for making age-worthy wines can be quite obnoxious to many (like me) when young. But, even that depends on region and winemaking style.
Some grapes have wonderful primary aromatics. The challenge is maintaining those, so they make it to bottle. Even then, the drinking window to keep that can be very short (like 6 or 12 months from release). Some such wines have the stuff to transform into something else wonderful with age, others will just fall apart.
To the OP, the best way to do this imo is link us the website of a store you shop at. Then we can make some specific suggestions for you to choose from, in a quite easy way. Try those and go from there.
I was not sure whether CdB wines were still under $50. Most of my list came either from general knowledge or looking at the website from a local store - MacArthur Liquors. Still like CdB wines, but wish they would mature a bit faster - another reason I did not list it, as they are a bit rough when young, even though they age wonderfully.
I bought a 2004 white PV from them from Envoyer not too long along and need to try it. It was well under $50, but did not list it because I don’t know if it is widely available.
Shush! Loire reds are not complex, they are Brett- and funk-infected swill for those with trash palates. You should instead look to Burgundy, Bordeaux, Germany, California, etc for complex wines under $50.
Lots of good suggestions above. Here are some of mine:
Chateau des Tours Cotes du Rhône
Faiveley Mercurey Clos du Roy
Faiveley Mercurey Clos des Myglands
Produttori Del Barbaresco Barbaresco
Produttori Del Barbaresco Langhe Nebbiolo
Copain Les Voisins Syrah
I also agree with Cantemerle, Geyserville and probably a bunch of others mentioned.
I totally agree with all of this, including those suggestions. For Heredia, I think the Reservas tend to be a lot more complex than the Crianzas. For Musar, I am only talking about the Chateau Musar red and white, not the less expensive wines they make.