On saturday in Royan there will be on offer (for about €300/350) a handwritten set of lecture notes of Cauchy’s 1824 course on Calcul différentiel et intégral, taken by Lamoricière. It may well beat that estimate by some margin.
Indeed, last december, the own annotated copy of Hugens’ Horologium Oscillatorium Sive de Motu Pendulorum ad Horologia Aptato Demonstrationes Geometricae (1673), went for $965,000 after an estimate of 150,000/200,000.
A month earlier, a 1931 offprint of Gödel’s Über Formal Unentscheidbare Sätze der Principia Mathematica und verwandlter Systeme I, achieved £104,500 after an estimate of £12,000/£16,000.
So, there seems to be a market for the rare and historically important items, that’s not too surprising but the level is pretty high (I guess all it takes is just a couple of mathematically enclined high-ranking google executives, or the likes…). And it’s not only auctions, fixed price items exist too, like these 3 manuscript pages by Gauss available for €65,000.
Update: the aforementioned sale has been broadcast online earlier today, and those handwritten notes indeed attracted interest, with a little fight between the floor and online bids ending at €1,300.