You would have to say most of us here would have 'oddball' cartridges, just to get dies & components is a wait, luckily it is still achievable due to Bertram Brass & Woodleigh projectiles!
Also CBE moulds here in Oz are great to get us casting as well.
As to these cartridges for me, basically a combination of either rifles not chambered now-a-days &/or low number overall produced compared to conventional calibers.

.32-20
.308 Norma Mag
9.3x64mm
.404 Jeffery
.500 Nitro 3"
.577-450 Martini Henry

These might be almost forgotten to the 'general public', but not here though!