What are the most balanced relatively neutral cartridges at each price level ?

edsemble,

You are right these issues matter irrespective of source be it analog or digital.  

level 1 - up to$1k. - Shure V15vxmr

level 2 - up to $3. - Shure V15vxmr

level 3 - up to $5k. - Shure V15vxmr

level 4. - any price. - Shake Streamliner

Question: if a balanced and neutral cartridge was available in the lower price range, why would anyone pay more for one? (I suppose cynics would say for bragging rights.)

Seriously, if a cartridge is balanced and neutral buy it. My view is that there is probably no perfectly balanced and neutral cartridge, merely approximations that get more expensive as they asymptotically approach.

My solution is to enjoy the sound of each cartridge. I can tell which one I am listening to, and I like the choice of which to use when I select an LP.

I believe your solution is the correct one.  

@dogberry 

Years ago I had a customer with a 6 figure system that used a $300 Grado.

Bought a new one every year as the system was used every day.

System was excellent ( and I listen regularly to $5-10k cartridges ).

Sometimes less is more if the rest of the system is good enough.