So true, its all about the glass! It took me a long time to learn that the camera body is not as important as the lens. The sigma art lenses are also an excellent choice, the quality/price ratio is insanely good.
Personally I have a bit of a crush on Zeiss lenses, but they are insanely expensive. The cheapest one (which I have): the 50mm 1.8 planar is amazingly good and still costs £500. I think the most I ever spent on a lens was just under a grand.. but you can easily pay much much more than that!
Now I can no longer blame my gear when I take bad photos, it's all me from now on 😅
These did set me back quite a lot but I just need to keep taking more photos to make up for it 😬 I checked out the raved Nikkor 70-200mm and that was like 2500€ of something like that, insane! But gladly it's meant for a full frame so I couldn't buy it😂😂
Yeah the pro level nikon stuff is very expensive and you do get to a point where you can start spending thousands more for a minimal difference. I'm sure you'll make back the investment in no time! :)