Choice of Phono Cartridges

Choosing a cartridge you must take in count an effective mass of your tonearm. Some cartridges will not work properly on your current tonearm because of the tonearm mass and cartridge compliance miss match.

Even if you can find inexpensive MC cartridge within your price range this is not final. You will have more problems with low output MC in a mediocre system. Another problem is a cost of factory re-tip (and you will have to ship your cartridge away for a long time).

Of course you can upgrade your turntable, but for every turntable you need a cartridge. You can easily start with a cartridge and if it’s a mid compliance cartridge then it is more or less universal for modern tonearms (they are mid mass).

In your situation I think MM or MI is a better choice within your price range. If you will add some NOS cartridges in your list you will get much more (such as exotic cantilevers for example) in the same price range. This is where some nice vintage MM are the best. I don’t know the mass of your tonearm (you have to check it) but a mid compliance MM cartridges from Japanese brand Victor in X1II series are superb and you will find a lot of great feedbacks from other users on audiogon about them!

Regarding new MM cartridge you can add Australian made Garrott Brothers p77i in the list.

How many MM cartridges even with Boron Rod cantilever anyone can find today and for what price? 

It's amazing that SONY made one with Boron Pipe (The XL-50 MM) long time ago in the 80's. 

Back in the days SONY established Sony Sound Tec Corporation to produce phono cartridges. Not every equipment manufacturer can make a phono cartridge, but the Sony Sound Tec Corp combining all the passion and knowledge has released some very interesting models in the early 80's. The XL-50 is one of two finest Moving Magnet cartridges from SONY.

Very special features are as follows:
The Jointless delta-type core;
Boron Pipe cantilever and nude Super Elliptical Diamond;
A screw holds the stylus holder firmly in place;
Distortion caused by flex is virtually eliminated;
Cup-shaped damper and tension wire!

This lightweight and high compliance cartridge is designed for low mass tonearms. Loading recommended by the manufacturer is from 47k Ohm to 100k Ohm. Cartridge output is 2.0 mV. Frequency response is pretty wide: 10Hz - 50000Hz! The price for XL-50 was ¥25000 in 1981.

Boron Pipe cantilever is nothing but a grown crystal of Pure Boron into a pipe configuration (wow). A tip mounting hole made using a laser beam. This technology is no longer available, instead of ultra lightweight PIPE configuration you can get only heavier Boron ROD configuration from cantilever manufacturers nowadays. Boron PIPE is associated ONLY with vintage High-End cartridges (MM or MC).  XL-50 and this is an excellent MM cartridge with exotic cantilever!  

I remember Peter Ledermann (SoundSmith) has mentioned Walter Stanton MI design and some other cartridges when i asked him about clever design from the past. 

Regarding cartridge and tonearm systems resonance frequency, Richard, you have to read this: 

https://www.ortofon.com/support/support-hifi/resonance-frequency/

Unfortunately they are all fragile, even those short gemstone cantilevers (the most exoensive). 

According to cartridge designer (Mr. Reto Adrioli of the Bluelectric) the aluminum is the best to work with. Japanese school of cartridge designers is a proof of that when it comes to MC. 

Looking for relatively cheap MM cartridges with aluminum cantilever it would be great to have a "nude" line contact type of the diamond for better reproduction and longer stylus life (less record wear too). 

If a cartridge have not only great stylus shape (at least shibata) but also great cantilever (beryllium was great) then the whole moving mass system will be much lower, as the result - the sound will be refined too (also better tracking because if the higher compliance). 

However, Stanton/Pickering acheved amazing sound with aluminum cantilever and their patented Stereohedron stylus. Everything depends on particular cartridge design. 

At the same time Technics with their best MM and MC ended up with Boron Pipe after serious research: "Somewhere in the high frequencies, every cartridge has an undesirable resonance point where the frequency response curve climbs a sudden peak. If that peak is in the audible range, your records sound not as intended. That resonance frequency is determined by the total effective moving mass of the vibrating system - the summed masses of the diamond stylus and, most importantly, the cantilever and magnet, etc. To shift that harmful resonance frequency up into the high supersonics, the effective moving mass must be reduced to the lowest possible minimum. Also, too much effective moving mass increases the mechanical impedance, thereby negatively affecting the cartridge's tracing ability."