Statistically speaking, in an average year, over 10,000 Old Master paintings priced between $10,000 – 20,000,000 are offered at public auction worldwide – this is taking into account smaller regional auction houses such as Drouot, Lempertz, Artcurial, Tajan, Dorotheum, Koller, Bonhams as well as Sotheby’s and Christie’s. Some works are unattributed or by minor painters, but reliably there are paintings and drawings by the so-called top tier Old Master painters (e.g. Titian, Rubens, Pontormo, Rembrandt, Canaletto, Turner and Delacroix, to name but a few) available. In 2019, paintings by Cimabue and Caravaggio surfaced out of the blue in France.
Meanwhile, a large volume of works are sold privately through Old Master galleries. The sales info is not made public but you can get an idea of the market by attending an art fair like TEFAF Maastricht or visiting the gallery and making personalised enquiries.
Perhaps the real issue is a matter of money. At the top end, old master paintings may actually be more valuable than any work by a contemporary or modern artist. The record price for a work of art at auction is, after all, for an Old Master.