Cartridge upgrade

You will get a great sonic improvement by investing $3.4K in either the turntable or cartridge. If you are looking long termed, I would start with the turntable ($5K would get you up another level)… but you easily could get a bigger incremental improvement swapping cartridges. Do both, even better.

Cartridge 1st!

You will definitely hear cartridge differences on a most basic TT, think 'preferred' rather than better, and you may or may not hear differences between arms and/or spinners.

You can always move a cartridge to a 'better' arm or table later.

I did not know that the Voice cost as much as $3000.  Since that is so, I could not recommend it as a cost-saving alternative to the Kiseki.  Albeit, taken by itself, I take Mijostyn's word for its excellence. (I never heard one.)  To the OP, if Kiseki is pulling out of the US market, that might mean their cartridges are not selling well here for any one of a number of reasons.  But keep in mind, Kiseki of today is not the same as vintage Kiseki.  I also omitted to mention Hana; they also make excellent modestly priced cartridges.  And my other main point is that I do not at all subscribe to the idea that there is any sort of linear correlation between price of a cartridge and sonic excellence.

Mijo, Yes, I am still listening to the MP500 but switching back and forth with some others.

FWIW, have owned a Kiseki Purpleheart NS for several years.  Recently installed a Hana Umami Blue just for a change.  So far the Kiseki sounds better to my ears.  Excellent cartridge.  The Blue is fine, but there’s a magic to the Kiseki; it is full sounding, sweet, detailed, with an excellent and realistic mid range that is clear and unmuddied.  The Umami probably has some time remaining to fully bloom, but the Kiseki is special; certainly preferable to the Ortofon Cadenze Bronze I ran for years.  

Of course a more expensive cartridge will play and sound better on your turntable. The same way a set of Pirelli PZeros would on a Toyota Camry. You will not benefit from everything the cartridge has to offer.