Yes, Emanem (which incorporates PSI) seems to have an extraordinary range of recordings, mostly kept in print. And in a quite different field, labels like Woodville and Trio seem closely related to the gigging of the musicians involved. I suspect their main sales come from there; having an outlet via online merchants, however small the rewards, presumably adds a low but steady income on top of the main selling point.
I'm always amazed by the number of classical labels that continue to flourish outside of the majors. One like Dutton Vocalion, which works in a number of niches, but seems to have no problem putting out regular releases of virtually vanished late 19th/early to mid-20thC British classical music (plus some more tonal contemporary music).