I am willing to roll the dice with a vintage cartridge. I have done well before in seeking out 30-40yr old MM stereo cartridges. The cost of a current production True Mono cartridge starts at about $800-$900. The cost of acquiring a vintage cartridge, and then having it rebuilt should be about $500-$600. The assumption being that the cartridge in question does not have a shorted coil, and measures within a few ohms of specification. The rest- cantilever, stylus, suspension, bushings, can be replaced. There are at least 2 rebuilders with significant experience in restoring these cartridges, so I am confident of success.
The change from mono to stereo pressings included a change in groove width and shape. Older mono pressings (pre stereo) can be played using stereo cartridges, but something is lost. Using a true mono cartridge (that responds to lateral signal only), with a stylus of appropriate width results in much better reproduction than a modern stereo cartridge adapted for mono, and using a current stylus profile.
I'm not a Luddite but I realized a long time ago that "new" does not automatically mean "better".
My system is a combination of new, old and vintage components:
Triangle Titus 202 speakers (10yrs old)
ARC D70 MKII
Cary 40m/SE
Audible Illusions M3
Linn LP12/ ITTOK LVII / AT 33MLocc / Lundahl SUT
Blue Sound Node 2 media streamer connected to an NAS (purchased this year)
AR3a used as subwoofers
Mac 2100 as amp for subs
Mirage powered crossover
Technics SP15 TT / AT 1503 MKII arm to be used a mono TT
Computer system:
Musical Fidelity a3.2 integrated
Spica TC50
HRT Streamer
AR ES1/ Shure V15Vmr
I also have a large collection of vintage tube equpment:
Heathkit (W4, W5, AA111, UA2 amps)
Eico (HF14, HF86 HF87 HF81)
Fisher (500s, 500c, 500b, 400, 600, X202, 20a, 30a, 440a. FM202T, FM90r, FM200 + mpx200)
Pilot (AA902 and console stereo amp)
Dynaco (too many ST70 and PAS3, several MK4)
AR (3a, 5, and multiple prs of 2ax, at least 2 XA tables)
Janszen (400z, 600z)
Conrad Johson PV5
Hafler DH101
Several NAD receivers
NAD 3020