On October 9th and 10th there will be a number of events staged at Chateau de Cheverny, culminating in an auction of Hergé related memorabilia and original artwork. The event is organised jointly by Piasa and Moulinsart. As mentioned
in this thread, there is also another unrelated Tintin auction taking place in Paris on the 9th, hosted by Artcurial.
A catalogue of the Piasa auction can be downloaded from
here.
Of particular note; for book collectors there's a 1930 signed copy of
Au pays des Soviets (valued at 15,000-20,000 euros), an extremely rare Cœurs Vaillants edition of
Les Aventures de Tintin et Milou en Amérique from 1934 (35,000-40,000), a numbered and signed first edition of
Tintin au Tibet (15,000-20,000 euros). There are also some first edition English books, including the rare 1952 Casterman editions of
The Secret of the Unicorn and
Red Rackham's Treasure on page 26 of the catalogue.
There's quite a bit of original artwork too, including a 1951 Easter post card design (30,000-40,000 euros) and original ink for a 1954 puzzle design of
Le Temple du Soleil (18,000-20,000).
Another noteworthy piece is "Le plan et l’acte de vente du Château de Moulinsart" (lot 335, page 38), which includes a fictitious public sale contract of the Château and also a plan of Moulinsart signed jointly by Hergé and Bob de Moor in 1976, plus some other related items.