When I took on photography, there were a lot of filters to consider. ND, Haze, warming, cooling, grad-ND, polarizers. Heck, I had so many filters that sometimes they needed a little bag of their own inside my photography bag. Today though, most of the filters can be mimicked with photoshop.
Landscape photographer Mark Denney makes an interesting point, he shows three of the more common filters, ND, Grad-ND and a circular polarizer and while two of those filters can be replaced with photoshop-work. Mark asks a simple question, would you rather be spending your time editing in front on a computer, or hiking and shooting behind a camera.
It’s quite clear than warming and cooling filters can be replaced with shooting RAW in almost every case (not every case, but probably 99.9% of the cases).
What about ND filters, those can probably be replaced by stacking exposures or flattening a video.
Grad ND can be replaced by double exposure.
The only filter that is impossible to replace is the CPL filter (circular polarizer).
The Nisi kit that Mark uses is about $150. Not a lot of money if you look at the cost o lenses for example.
But ask yourself this, would you rather be sitting in front of a computer, or shooting behind a tripod?