Why are classical solo cello LPs so expensive?

I am trying to collect cello LPs, mostly solo (like Bach's 6 cello suites) and sonata (Beethoven's, Brahams), and some concertos. But they all seem to be far more expensive than for other instruments.
Bach cello suites by Janos Starker seem to be one of the most expensive. DuPre's cello works are all priced high.

Is it a known fact that solo cello or cello sonata LPs are highly sought after and very expensive? If it is, any particular reason?
For me, most cello recordings sound so good with LPs, much better than CD recordings. I don't feel such on the piano or violin. Are most other people like me, which is why cello LPs are sold at high premium?