The old 35mm film prime multiple was 2x or 3x.

Here are some samples at different multiples:

- 2x = 24 + 50 + 105 + 200 + 400
- 2-2.5x = 24 + 50 + 135 + 300
- 3x = 35 + 105 + 300

Note1: Back in my day, 35 was the common wide lens, and 28 was generally the widest lens people got. VERY FEW got the 24, because it was hard for most to control the wide angle distortion/perspective. So in the example above, rather than 24, most people would stop at and use the 28.

Note2: 2x would require more lenses, so was more expensive than 3x.

As a student without a lot of $$$$, I would go with 3x.

But in reality, most of us got a 50 with the camera, so we ended up with the 2.5x option.

DX is a tough format for primes. As you found out, there are few DX primes, mostly zooms. You have to PAY the premium for FX primes. Even in the FX world, many of the primes we used to have do not exist, replaced by zooms.

My standard DX kit is the 18-140 as my GP lens, with a DX 35/1.8 (normal) as my low light indoor lens.

I would have preferred a DX 24/1.8 (wide), but Nikon did not make one, so I had to settle for the 35/1.8 (normal).

I have other lenses, but those are purpose lenses for shooting sports; 70-200/4 (field) and 50/1.8 (gym).

If you want to build a prime kit, then the FX 24/2.8 would fit your scheme; 24+50+100.