Lord
First of all, I want to clarify: in your post, I talked exclusively about the sellers of art objects, without affecting the issue of the buyers (the seller for the auction house - also a client).
Now actually the "substantial concessions"
Of course, when his now wants to put up for auction ring - and often random - winner of the auction is organichivaetsya that lists him his dry conditions - so much interest from the market so much for the photograph in the catalog so much for framing, etc. d.
But suppose that the auction is drawn to well-known collector, who wishes to part with his collection, or part thereof, or a large dealer (and also want to name one of the main suppliers of Russian art auction, not so long ago who buys at more than reasonable price is great
y the first part of another meeting last major collector
), or even better - The auction house is drawn to such a collector or dealer. Naturally, he is offered special conditions that may induce him to work with this particular house. These proposed - and accepted, sometimes after lengthy negotiations - terms and conditions are written in the contract.
Of course, Sotheby's and Christie's - large structures, but each department has the right to make their own decisions and is responsible for its results - it explains that between, say, London and New York departments of Russia's art suschestvvuet competition. So Sergeyitch quite right with his car dealership
With regard to taxes and other things - I do not see the problem: it's all calculated from the actual price item sold as is generally going to trade (after all, a shoemaker, who made you a trade discount of 15%will not pay taxes to the full cost of their services, and with 85%, right?), nothing illegal and reprehensible in this.
Once the client (the seller) to "tame", interest, naturally, does not podnimeyutsya, but this "commercial loss" is justified by the quantity and quality of the work - not to forget the advantages of their origin, since they are derived from the well-known in circles of fans arts person - so everyone is happy and life is beautiful.
Now about the buyers. Here I have less data, but drive a little cartoon, but it is a real example to all of it immediately became clear: the auction house can do to sacrifice their margins if it finds that the buyer did him a service.
Well, sort of, and all I can say about it.