Here are some sections from the conditions of sale.
I guess he makes money from the seller by this profit participation.
Also the buyer must pay immediately whereas he has 30 days to pay the seller less expenses and profit sharing.
I think it works by setting a reserve price and the seller and Patrizzi split anything above that in an agreed manner (50/50 or whatever.
Patrizzi Profit Participation: means the participation or margin payable to Patrizzi by the Seller. Such participation or margin is usually agreed upon specifically in writing before the Auction between Patrizzi and the Seller and is calculated on the basis of a percentage of the difference between the Hammer Price and the Reserve Price;
The estimated selling prices of each Lot (low estimate and high estimate) are indicated beneath the Lot's description in the Catalogue and do not include any Expenses (in particular any VAT). These price indications are based on estimations made some time ahead of the Auction and may therefore still be revised before the Auction.
Unless otherwise agreed upon in writing, each Lot will be offered for Auction subject to a Reserve Price.
The Reserve Price will not exceed the final low pre-Auction estimate announced or published by Patrizzi.
In a sale organized in a traditional way (e.g. with a printed catalogue and/or with a single Auctioneer and/or where the Reserve Price and the Auctioneer's initial bidding price may differ), Patrizzi may also bid on behalf of any Seller in cases where a Reserve Price has been fixed. In such cases, the Seller is treated as a Buyer and the Auctioneer shall bid on his behalf up to the Reserve Price.
If the Reserve Price is not reached, Patrizzi may reject the last Bid and fix another starting price not above the Reserve Price or it may omit to knock down the Lot to anyone and pass on to the next Lot by a simple fall of the hammer.
Patrizzi may however sell any unsold Lot by post-Auction sale, provided that, in such a case, such post-Auction sale price shall not be lower than the Reserve Price, subject to a differing prior agreement of the Seller.
The full and final Purchase Price of the Lots must be paid by the Buyer to Patrizzi in Swiss francs immediately after the Auction, but no later than five Business Days after such Auction.
Patrizzi can decide in its sole discretion, subject to applicable laws, if it accepts any payment in cash.
Payment of the Purchase Price will not be deemed to have been validly made until Patrizzi is in full and final receipt of cleared funds covering the entire Purchase Price.
PATRIZZI PROFIT PARTICIPATION
After the Auction, the Seller is not only liable to pay to Patrizzi the Patrizzi Profit Participation, but also all Expenses to be borne by the Seller, as indicated in the account statement submitted by Patrizzi to the Seller after the Auction. The Seller authorizes Patrizzi to deduct from the Hammer Price such Patrizzi Profit Participation and the Expenses to be borne by the Seller. Patrizzi will pay the resulting Net Sale Proceeds to the Seller within 30 days of receipt by Patrizzi from the Buyer of full and final payment of the Purchase Price in cleared funds